Lead?Free Halide Double Perovskite Materials: A New Superstar Toward Green and Stable Optoelectronic Applications
|
摘要
Lead-based halide perovskites have emerged as excellent semiconductors for a broad range of optoelectronic applications, such as photovoltaics, lighting, lasing and photon detection. However, toxicity of lead and poor stability still represent significant challenges. Fortunately, halide double perovskite materials with formula of A_2M(I)M(III)X_6 or A_2M(IV)X_6 could be potentially regarded as stable and green alternatives for optoelectronic applications, where two divalent lead ions are substituted by combining one monovalent and one trivalent ions, or one tetravalent ion. Here, the article provides an up-to-date review on the developments of halide double perovskite materials and their related optoelectronic applications including photodetectors, X-ray detectors, photocatalyst, light-emitting diodes and solar cells. The synthesized halide double perovskite materials exhibit exceptional stability, and a few possess superior optoelectronic properties. However, the number of synthesized halide double perovskites is limited, and more limited materials have been developed for optoelectronic applications to date. In addition, the band structures and carrier transport properties of the materials are still not desired, and the films still manifest low quality for photovoltaic applications. Therefore, we propose that continuing e orts are needed to develop more halide double perovskites, modulate the properties and grow high-quality films, with the aim of opening the wild practical applications.
Lead-based halide perovskites have emerged as excellent semiconductors for a broad range of optoelectronic applications, such as photovoltaics, lighting, lasing and photon detection. However, toxicity of lead and poor stability still represent significant challenges. Fortunately, halide double perovskite materials with formula of A_2M(I)M(III)X_6 or A_2M(IV)X_6 could be potentially regarded as stable and green alternatives for optoelectronic applications, where two divalent lead ions are substituted by combining one monovalent and one trivalent ions, or one tetravalent ion. Here, the article provides an up-to-date review on the developments of halide double perovskite materials and their related optoelectronic applications including photodetectors, X-ray detectors, photocatalyst, light-emitting diodes and solar cells. The synthesized halide double perovskite materials exhibit exceptional stability, and a few possess superior optoelectronic properties. However, the number of synthesized halide double perovskites is limited, and more limited materials have been developed for optoelectronic applications to date. In addition, the band structures and carrier transport properties of the materials are still not desired, and the films still manifest low quality for photovoltaic applications. Therefore, we propose that continuing e orts are needed to develop more halide double perovskites, modulate the properties and grow high-quality films, with the aim of opening the wild practical applications.
Lead-based halide perovskites have emerged as excellent semiconductors for a broad range of optoelectronic applications, such as photovoltaics, lighting, lasing and photon detection. However, toxicity of lead and poor stability still represent significant challenges. Fortunately, halide double perovskite materials with formula of A_2M(I)M(III)X_6 or A_2M(IV)X_6 could be potentially regarded as stable and green alternatives for optoelectronic applications, where two divalent lead ions are substituted by combining one monovalent and one trivalent ions, or one tetravalent ion. Here, the article provides an up-to-date review on the developments of halide double perovskite materials and their related optoelectronic applications including photodetectors, X-ray detectors, photocatalyst, light-emitting diodes and solar cells. The synthesized halide double perovskite materials exhibit exceptional stability, and a few possess superior optoelectronic properties. However, the number of synthesized halide double perovskites is limited, and more limited materials have been developed for optoelectronic applications to date. In addition, the band structures and carrier transport properties of the materials are still not desired, and the films still manifest low quality for photovoltaic applications. Therefore, we propose that continuing e orts are needed to develop more halide double perovskites, modulate the properties and grow high-quality films, with the aim of opening the wild practical applications.
引文
1.A. Kojima, K. Teshima, Y. Shirai, T. Miyasaka, Organometal halide perovskites as visible-light sensitizers for photovoltaic cells. J. Am. Chem. Soc. 131(17), 6050–6051(2009). https://doi.org/10.1021/ja809 598r
2 .H.S. Kim, C.R. Lee, J.H. Im, K.B. Lee, T. Moehl et al., Lead iodide perovskite sensitized all-solid-state submicron thin film mesoscopic solar cell with e ciency exceeding 9%. Sci.Rep. 2, 6022–6025(2012). https://doi.org/10.1038/srep0 0591
3 .H. Zhou, Q. Chen, G. Li, S. Luo, T.B. Song et al., Interface engineering of highly e cient perovskite solar cells. Science345 (6196), 542–546(2014). https://doi.org/10.1126/scien ce.12540 50
4 .N.J. Jeon, J.H. Noh, W.S. Yang, Y.C. Kim, S. Ryu, J. Seo, S.I.Seok, Compositional engineering of perovskite materials for high-performance solar cells. Nature 517, 476–480(2015).https://doi.org/10.1038/natur e1413 3
5 .D.Luo,W.Yang,Z.Wang,A.Sadhanala,Q.Huetal.,Enhanced photovoltage for inverted planar heterojunction perovskite solar cells. Science 360(6396), 1442(2018). https://doi.org/10.1126/scien ce.aap92 82
6 .National Renewable Energy Laboratory(NREL)(2018). https://www.nrel.gov/pv/asset s/pdfs/pv-e c ienci es-chart.20181214 .pdf
7 .M.M. Lee, J. Teuscher, T. Miyasaka, T.N. Murakumi, H.J.Snaith, E cient hybrid solar cells based on meso-superstructured organometal halide perovskites. Science 338(6107),643 –647(2012). https://doi.org/10.1126/scien ce.12286 04
8 .S.D. Stranks, G.E. Eperon, G. Grancini, C. Menelaou, M.J.P.Alcocer, T. Leijtens, L.M. Hertz, A. Petrozza, H.J. Snaith,Electron-holediffusionlengthsexceeding1micrometer inanorganometaltrihalideperovskiteabsorber.Science342 (6156), 341–344(2013). https://doi.org/10.1126/scien ce.12439 82
9 .G.C.Xing,N.Mathews,S.Y.Sun,S.S.Lim,Y.M.Lam,M. Gratzel, S. Mhaisalkar, T.C. Sum, Long-range balanced electron-andhole-transportlengthsinorganic-inorganic CH3NH3PbI3. Science 342(6156), 344–347(2013). https://doi.org/10.1126/scien ce.12431 67
10 .W.S. Yang, B.W. Park, E.H. Jung, N.J. Jeon, Y.C. Kim et al.,Iodide management in formamidinium-lead-halide-based perovskite layers for e cient solar cells. Science 356(6345),1376–1379(2017). https://doi.org/10.1126/scien ce.aan23 01
11 .S.D. Stranks, H.J. Snaith, Metal-halide perovskites for photovoltaic and light-emitting devices. Nat. Nanotech. 10(5),391 –402(2015). https://doi.org/10.1038/nnano.2015.90
12.H. Cho, S.H. Jeong, M.H. Park, Y.H. Kim, C. Wolf, C.L. Lee et al., Overcoming the electroluminescence e ciency limitations of perovskite light-emitting diodes. Science 350(6265),1222–1225(2015). https://doi.org/10.1126/scien ce.aad18 18
13 .H. Zhu, Y. Fu, F. Meng, X. Wu, Z. Gong et al., Lead halide perovskite nanowire lasers with low lasing thresholds and high quality factors. Nat. Mater. 14(6), 636–642(2015). https://doi.org/10.1038/nmat4 271
14 .F. Zhang, B. Yang, K. Zheng, S. Yang, Y. Li, W. Deng, R.He,Formamidiniumleadbromide(FAPbBr3)perovskite microcrystals for sensitive and fast photodetectors. NanoMicro Lett. 10(3), 43(2018). https://doi.org/10.1007/s40820-018-0196-2
15 .L. Chu, R. Hu, W. Liu, Y. Ma, R. Zhang, J. Yang, X. Li,Screen printing large-area organometal halide perovskite thin films for e cient photodetectors. Mater. Res. Bull. 98, 322(2018). https://doi.org/10.1016/j.mater resbu ll.2017.10.039
16 .Q. Chen, J. Wu, X. Ou, B. Huang, J. Almutlaq et al., All-inorganic perovskite nanocrystal scintillators. Nature 561(7721),88 (2018). https://doi.org/10.1038/s4158 6-018-0451-1
17 .H. Luo, X. Lin, X. Hou, L. Pan, S. Huang, X. Chen, E cient and air-stable planar perovskite solar cells formed on grapheneoxide-modified PEDOT:PSS hole transport layer. Nano-Micro Lett. 9(4), 39(2017). https://doi.org/10.1007/s4082
18 .Y. Yang, J. You, Make perovskite solar cells stable. Nature544 (7649), 155(2017). https://doi.org/10.1038/54415 5a
19 .M. Saliba, T. Matsui, K. Domanski, J.Y. Seo, A. Ummadisingu et al., Incorporation of rubidium cations into perovskitesolarcellsimprovesphotovoltaicperformance.Science 354(6309), 5557(2016). https://doi.org/10.1126/scien ce.aah55 57
20 .J.M. Ball, A. Petrozza, Defects in perovskite-halides and their e ects in solar cells. Nat. Energy 1(11), 16149(2016). https://doi.org/10.1038/nener gy.2016.149
21 .J. Cheng, H. Zhang, S. Zhang, D. Ouyang, Z. Huang, M.K.Nazeeruddin, J. Hou, W.C. Choy, Highly e cient planar perovskite solar cells achieved by simultaneous defect engineering and formation kinetic control. J. Mater. Chem. A 6(46),23865(2018). https://doi.org/10.1039/C8TA0 8819E
22 .J.C. Hebig, I. Kühn, J. Flohre, T. Kirchartz, Optoelectronic properties of(CH3NH3)3Sb2I9 thin films for photovoltaic applications. ACS Energy Lett. 1(1), 309–314(2016). https://doi.org/10.1021/acsen ergyl ett.6b001 70
23 .T. Singh, A. Kulkarni, M. Ikegami, T. Miyasaka, E ect of electron transporting layer on bismuth-based lead-free perovskite(CH3NH3)3Bi2I9 for photovoltaic applications. ACS Appl. Mater. Interfaces. 8(23), 14542–14547(2016). https://doi.org/10.1021/acsam i.6b028 43
24 .J. You, L. Meng, T.B. Song, T.F. Guo, Y.M. Yang et al.,Improved air stability of perovskite solar cells via solutionprocessed metal oxide transport layers. Nat. Nanotech. 11(1),75 –81(2016). https://doi.org/10.1038/nnano.2015.230
25 .W. Liao, D. Zhao, Y. Yu, C.R. Grice, C. Wang et al., Leadfree inverted planar formamidinium tin triiodide perovskite solarcellsachievingpowerconversione cienciesupto6.22%. Adv. Mater. 28(42), 9333–9340(2016). https://doi.org/10.1002/adma.20160 2992
26 .H. Tsai, W. Nie, J.C. Blancon, C.C. Stoumpos, R. Asadpour et al., High-e ciency two-dimensional ruddlesden-popper perovskite solar cells. Nature 536(7616), 312–316(2016).https://doi.org/10.1038/natur e1830 6
27 .F. Matteocci, L. Cinà, E. Lamanna, S. Cacovich, G. Divitini,P.A. Midgley, C. Ducati, A.D. Carlo, Encapsulation for longterm stability enhancement of perovskite solar cells. Nano Energy 30, 162–172(2016). https://doi.org/10.1016/j.nanoe n.2016.09.041
28 .G. Flora, D. Gupta, A. Tiwari, Toxicity of lead:a review with recent updates. Interdiscip. Toxicol. 5(2), 47–58(2012). https://doi.org/10.2478/v1010 2-012-0009-2
29 .L.Liang,P.Gao,Lead-freehybridperovskiteabsorbers for viable application:can we eat the cake and have it too.Adv.Sci.5(2),1700331(2018).https://doi.org/10.1002/advs.20170 0331
30 .F. Hao, C.C. Stoumpos, R.P.H. Chang, M.G. Kanatzidis,Anomalous band gap behavior in mixed Sn and Pb perovskites enables broadening of absorption spectrum in solar cells. J. Am. Chem. Soc. 136(22), 8094–8099(2014). https://doi.org/10.1021/ja503 3259
31 .T. Krishnamoorthy, H. Ding, C. Yan, W.L. Leong, T. Baikie et al., Lead-free germanium iodide perovskite materials for photovoltaic applications. J. Mater. Chem. A 3(47), 23829–23832(2015). https://doi.org/10.1039/C5TA0 5741H
32 .H. Wang, H. Zhang, C.C. Chueh, T. Zhao, C. Mao, W. Chen,A.K.Y. Jenac, Enhanced crystallization and performance of formamidinium lead triiodide perovskite solar cells through PbI2-SrCl2 modulation. Mater. Today Energy 7, 239(2018).https://doi.org/10.1016/j.mtene r.2017.10.002
33 .M.T. Klug, A. Osherov, A.A. Haghighirad, S.D. Stranks,P.R. Brown et al., Tailoring metal halide perovskites through metal substitution:influence on photovoltaic and material properties. Energy Environ. Sci. 10(1), 236(2017). https://doi.org/10.1039/C6EE0 3201J
34 .J. Jin, H. Li, C. Chen, B. Zhang, L. Xu, B. Dong, H. Song,Q. Dai, Enhanced performance of perovskite solar cells with zinc chloride additives. ACS Appl. Mater. Interfaces. 9(49),42875–42882(2017). https://doi.org/10.1021/acsam i.7b15310
35.Q. Chen, L. Chen, F.Y. Ye, T. Zhao, F. Tang et al., Ag-incorporated organic-inorganic perovskite films and planar heterojunction solar cells. Nano Lett. 17(5), 3231–3237(2017).https://doi.org/10.1021/acs.nanol ett.7b008 47
36 .J. Zhang, M. Shang, P. Wang, X. Huang, J. Xu, Z. Hu, Y.Zhu,L.Han,n-Typedopingandenergystatestuningin CH3NH3Pb1–xSb2x/3I3 perovskite solar cells. ACS Energy Lett. 1(3), 535–541(2016). https://doi.org/10.1021/acsen ergyl ett.6b002 41
37 .Y. Hu, T. Qiu, F. Bai, X. Miao, S. Zhang, Enhancing moisture-tolerance and photovoltaic performances ofFAPbI3 by bismuth incorporation. J. Mater. Chem. A 5(48), 25258–25265(2017). https://doi.org/10.1039/C7TA0 8824H
38.F. Wei, Z. Deng, S. Sun, F. Xie, G. Kieslich, D.M. Evans,M.A. Carpenter, P.D. Bristowe, A.K. Cheetham, The synthesis,structureandelectronicpropertiesofalead-free hybrid inorganic-organic double perovskite(MA)2KBiCl6(MA=methylammonium).Mater.Horiz.3(4),328–332(2016). https://doi.org/10.1039/C6MH0 0053C
39 .P.D.Matthews,D.J.Lewis,P.O’Brien,Updatingthe road map to metal-halide perovskites for photovoltaics. J.Mater. Chem. A 5(33), 17135–17150(2017). https://doi.org/10.1039/C7TA0 4544A
40 .F. Giustino, H.J. Snaith, Toward lead-free perovskite solar cells. ACS Energy Lett. 1(6), 1233–1240(2016). https://doi.org/10.1021/acsen ergyl ett.6b004 99
41 .K.W.Bagnall,J.B.Laidler,M.A.A.Stewart,Americium chloro-complexes. J. Chem. Soc. A 0, 133–136(1968). https://doi.org/10.1039/J1968 00001 33
42 .L.R. Morss, J. Fuger, Preparation and crystal structures of dicesium berkelium hexachloride and dicesium sodium berkelium hexachloride. Inorg. Chem. 8(7), 1433–1439(1969).https://doi.org/10.1021/ic500 77a01 3
43 .L.R. Morss, M. Siegal, L. Stenger, N. Edelstein, Preparation of cubic chloro complex compounds of trivalent metals:Cs2NaMCl6. Inorg. Chem. 9(7), 1771–1775(1970). https://doi.org/10.1021/ic500 89a03 4
44 .L.R. Morrs, W.R. Robinson, Crystal structure ofCs2Na Bi Cl6.ActaCrystallogr.B28(2),653–654(1972).https://doi.org/10.1107/S0567 74087 20029 48
45 .F. Prokert, K.S. Aleksandrov, Neutron scattering studies on phase transition and phonon dispersion inCs2NaBiCl6. Phys.Status Solidi B 124(2), 503(1984). https://doi.org/10.1002/pssb.22212 40208
46 .W.M.A.Smit,G.J.Dirksen,D.J.Stufkens,Infrared andRamanspectraoftheelpasolitesCs2NaSbCl6and Cs2NaBiCl6:evidenceforapseudoJahn-Tellerdistorted ground state. J. Phys. Chem. Solids 51(2), 189–196(1990).https://doi.org/10.1016/0022-3697(90)90092-T
47 .I.N. Flerov, M.V. Gorev, K.S. Aleksandrov, A. Tressaud, J.Grannec, M. Couzi, Phase transitions in elpasolites(ordered perovskites). Mater. Sci. Eng. 24(3), 81–151(1998). https://doi.org/10.1016/S0927-796X(98)00015-1
48 .E.T.McClure,M.R.Ball,W.Windl,P.M.Woodward,Cs2AgBiX6(X=Br, Cl):new visible light absorbing, leadfree halide perovskite semiconductors. Chem. Mater. 28(5),1348–1354(2016).https://doi.org/10.1021/acs.chemm ater.5b042 31
49 .G. Volonakis, M.R. Filip, A.A. Haghighirad, N. Sakai, B.Wenger, H.J. Snaith, F. Giustino, Lead-free halide double perovskites via heterovalent substitution of noble metals.J. Phys. Chem. Lett. 7(7), 1254–1259(2016). https://doi.org/10.1021/acs.jpcle tt.6b003 76
50 .Y. Bekenstein, J.C. Dahl, J. Huang, W.T. Osowiecki, J.K.Swabeck, E.M. Chan, P. Yang, A.P. Alivisatos, The making and breaking of lead-free double perovskite nanocrystals of cesium silver-bismuth halide compositions. Nano Lett. 18(6), 3502(2018). https://doi.org/10.1021/acs.nanol ett.8b005 60
51.S.E. Creutz, E.N. Crites, M.C. De Siena, D.R. Gamelin, Colloidal nanocrystals of lead-free double-perovskite(elpasolite)semiconductors:synthesis and anion exchange to access new materials. Nano Lett. 18(2), 1118(2018). https://doi.org/10.1021/acs.nanol ett.7b046 59
52 .A.H. Slavney, T. Hu, A.M. Lindenberg, H.I. Karunadasa, A bismuth-halide double perovskite with long carrier recombination lifetime for photovoltaic application. J. Am. Chem.Soc.138(7),2138–2141(2016).https://doi.org/10.1021/jacs.5b132 94
53 .Y. Bi, E.M. Hutter, Y. Fang, Q. Dong, J. Huang, T.J. Savenije,Charge carrier lifetimes exceeding 15μs in methylammonium lead iodide single crystals. J. Phys. Chem. Lett. 7(5), 923–928(2016). https://doi.org/10.1021/acs.jpcle tt.6b002 69
54 .W. Pan, H. Wu, J. Luo, Z. Deng, C. Ge et al., Cs2AgBiBr 6single-crystal X-ray detectors with a low detection limit. Nat.Photonics 11(11), 726–732(2017). https://doi.org/10.1038/s4156 6-017-0012-4
55 .R.L.Z. Hoye, L. Eyre, F. Wei, F. Brivio, A. Sadhanala et al.,Fundamental carrier lifetime exceeding 1μs in Cs2AgBiBr6 double perovskite. Adv. Mater. Interfaces 5(15), 1800464(2018). https://doi.org/10.1002/admi.20180 0464
56 .L. Zhou, Y.F. Xu, B.X. Chen, D.B. Kuang, C.Y. Su, Synthesis and photocatalytic application of stable lead-free Cs2AgBiBr6 perovskite nanocrystals. Small 14(11), 1703762(2018).https://doi.org/10.1002/smll.20170 3762
57 .A.H. Slavney, L. Leppert, D. Bartesaghi, A. Gold-Parker,M.F. Toney, T.J. Savenije, J.B. Neaton, H.I. Karunadasa,Defect-induced band-edge reconstruction of a bismuth-halide double perovskite for visible-light absorption. J. Am. Chem.Soc. 139(14), 5015–5018(2017). https://doi.org/10.1021/jacs.7b016 29
58 .K.Z. Du, W. Meng, X. Wang, Y. Yan, D.B. Mitzi, Bandgapengineeringoflead-freedoubleperovskiteCs2AgBiBr 6 through trivalent metal alloying. Angew. Chem. Int.Ed.56(28),8158–8274(2017).https://doi.org/10.1002/anie.20170 3970
59 .T.T. Tran, J.R. Panella, J.R. Chamorro, J.R. Morey, T.M.McQueen, Designing indirect-direct bandgap transitions in double perovskites. Mater. Horiz. 4(4), 688–693(2017). https://doi.org/10.1039/C7MH0 0239D
60 .G.Volonakis,A.A.Haghighirad,R.L.Milot,W.H.Sio,M.R. Filip et al.,Cs2InAgCl6:a new lead-free halide double perovskite with direct band gap. J. Phys. Chem. Lett. 8(4),772 –778(2017). https://doi.org/10.1021/acs.jpcle tt.6b026 82
61 .J. Luo, S. Li, H. Wu, Y. Zhou, Y. Li et al.,Cs2AgInCl6 double perovskite single crystals:parity forbidden transitions andtheirapplicationforsensitiveandfastUVphotodetectors. ACS Photonics 5(2), 398–405(2017). https://doi.org/10.1021/acsph otoni cs.7b008 37
62 .N. Nandha, A. Nag, Synthesis and luminescence of Mn-doped Cs2Ag In Cl6 double perovskites. Chem. Comm. 54(41), 5205–5208(2018). https://doi.org/10.1039/C8CC0 1982G
63 .K. Tanaka, T. Takahashi, T. Ban, T. Kondo, K. Uchida, N.Miura, Comparative study on the excitons in lead-halidebased perovskite-type crystalsCH3NH3Pb Br3 CH3NH3Pb I3.Solid State Commun. 127(9–10), 619–623(2003). https://doi.org/10.1016/S0038-1098(03)00566-0
64 .C. Zhang, L. Gao, S. Teo, Z. Guo, Z. Xu, S. Zhao, T. Ma,Designofanovelandhighlystablelead-freeCs2NaBiI6double perovskite for photovoltaic application. Sustainable Energy Fuels 2(11), 2419(2018). https://doi.org/10.1039/C8SE0 0154E
65 .X.G. Zhao, J.H. Yang, Y. Fu, D. Yang, Q. Xu, L. Yu, S.H.Wei, L. Zhang, Design of lead-free inorganic halide perovskites for solar cells via cation-transmutation. J. Am. Chem.Soc.139(7),2630–2638(2017).https://doi.org/10.1021/jacs.6b096 45
66 .T. Li, X. Zhao, D. Yang, M.H. Du, L. Zhang, Intrinsic defect properties in halide double perovskites for optoelectronic applications. Phys. Rev. Appl. 10(4), 41001(2018). https://doi.org/10.1103/PhysR evApp lied.10.04100 1
67 .X.G. Zhao, D. Yang, J.C. Ren, Y. Sun, Z. Xiao, L. Zhang,Rational design of halide double perovskites for optoelectronicapplications.Joule2(9),1662(2018).https://doi.org/10.1016/j.joule.2018.06.017
68 .Q. Xu, D. Yang, J. Lv, Y.Y. Sun, L. Zhang, Perovskite solar absorbers:materials by design. Small Methods 2(5), 1700316(2018). https://doi.org/10.1002/smtd.20170 0316
69 .X.G.Zhao,D.Yang,Y.Sun,T.Li,L.Zhang,L.Yu,A.Zunger,Cu-Inhalideperovskitesolarabsorbers.J.Am.Chem.Soc.139(19),6718–6725(2017).https://doi.org/10.1021/jacs.7b021 20
70 .Z.W. Xiao, K.Z. Du, W.W. Meng, J.B. Wang, D.B. Mitzi,Y.F. Yan, Intrinsic instability ofCs2In(I)M(III)X6(M=Bi,Sb; X=Halogen)double perovskites:a combined density functionaltheoryandexperimentalstudy.J.Am.Chem.Soc. 139(17), 6054–6057(2017). https://doi.org/10.1021/jacs.7b022 27
71 .M.G.Brik,I.V.Kityk,Modelingoflatticeconstantand their relations with ionic radii and electronegativity of constituting ions ofA2XY6 cubic crystals(A=K, Cs, Rb, Tl;X=tetravalent cation, Y=F, Cl, Br, I). J. Phys. Chem. Solids72(11),1256–1260(2011).https://doi.org/10.1016/j.jpcs.2011.07.016
72 .A.E. Maughan, A.M. Ganose, M.M. Bordelon, E.M. Miller,D.O. Scanlon, J.R. Neilson, Defect tolerance to intolerance in the vacancy-ordered double perovskite semiconductors Cs2Sn I6 andCs2Te I6. J. Am. Chem. Soc. 138(27), 8453–8464(2016). https://doi.org/10.1021/jacs.6b032 07
73 .A.E. Maughan, A.M. Ganose, A.M. Candia, J.T. Granger,D.O. Scanlon, J.R. Neilson, Anharmonicity and octahedral tilting in hybrid vacancy-ordered double perovskites. Chem.Mater. 30(2), 472–482(2018). https://doi.org/10.1021/acs.chemm ater.7b045 16
74 .B. Lee, C.C. Stoumpos, N. Zhou, F. Hao, C. Malliakas, C.Y.Yeh, T.J. Marks, M.G. Kanatzidis, R.P.H. Chang, Air-stable molecularsemiconductingiodosaltsforsolarcellapplications:Cs2SnI6 as a hole conductor. J. Am. Chem. Soc.136 (43), 15379–15385(2014). https://doi.org/10.1021/ja508464 w
75.S. Ghosh, S. Paul, S.K. De, Control synthesis of air-stable morphology tunable Pb-freeCs2Sn I6 perovskite nanoparticles and their photodetection properties. Part. Part. Syst. Char.35 (9), 1800199(2018). https://doi.org/10.1002/ppsc.201800199
76 .A. Wang, X. Yan, M. Zhang, S. Sun, M. Yang, W. Shen, X.Pan, P. Wang, Z. Deng, Controlled synthesis of lead-free and stable perovskite derivativeCs2SnI6 nanocrystals via a facile hot-injection process. Chem. Mater. 28(22), 8132–8140(2016). https://doi.org/10.1021/acs.chemm ater.6b013 29
77 .Z. Tan, J. Li, C. Zhang, Z. Li, Q. Hu et al., Highly e cient blue-emitting Bi-doped Cs2SnCl6 perovskite variant:photoluminescence induced by impurity doping. Adv. Funct.Mater.28(29),1801131(2018).https://doi.org/10.1002/adfm.20180 1131
78 .N. Sakai, A.A. Haghighirad, M.R. Filip, P.K. Nayak, S. Nayak et al., Solution-processed cesium hexabromopalladate(IV),Cs2PdBr 6, for optoelectronic applications. J. Am. Chem.Soc. 139(17), 6030–6033(2017). https://doi.org/10.1021/jacs.6b132 58
79 .L. Zhou, J.F. Liao, Z.G. Huang, X.D. Wang, Y.F. Xu, H.Y.Chen, D.B. Kuang, C.Y. Su, All-inorganic lead-freeCs2Pd X6(X=Br, I)perovskite nanocrystals with single unit cell thickness and high stability. ACS Energy Lett. 3(10), 2613–2619(2018). https://doi.org/10.1021/acsen ergyl ett.8b017 70
80 .K.F. Guenther, The preparation of some alkali hexabromotitanates(IV). Inorg. Chem. 3(12), 1788–1789(1964). https://doi.org/10.1021/ic500 22a03 3
81 .M.G. Ju, M. Chen, Y. Zhou, H.F. Garces, J. Dai et al., Earthabundant nontoxic titanium(IV)-based vacancy-ordered double perovskite halides with tunable 1.0 to 1.8 eV bandgaps for photovoltaic applications. ACS Energy Lett. 3(2), 297–304(2018). https://doi.org/10.1021/acsen ergyl ett.7b011 67
82 .Z. Deng, F. Wei, S. Sun, G. Kieslich, A.K. Cheetham, P.D.Bristowe, Exploring the properties of lead-free hybrid double perovskites using a combined computational-experimental approach. J. Mater. Chem. A 4(31), 12025–12029(2016).https://doi.org/10.1039/C6TA0 5817E
83 .F.X. Wei, Z.Y. Deng, S.J. Sun, F.H. Zhang, D.M. Evans et al.,Synthesis and properties of a lead-free hybrid double perovskite:(CH3NH3)2AgBiBr 6. Chem. Mater. 29(3), 1089–1094(2017). https://doi.org/10.1021/acs.chemm ater.6b039 44
84 .Y.J. Li, T. Wu, L. Sun, R.X. Yang, L. Jiang et al., Leadfreeandstableantimony-silver-halidedoubleperovskite(CH3NH3)2AgSbI6. RSC Adv. 7(56), 3517–35180(2017).https://doi.org/10.1039/C7RA0 6130G
85 .P. Cheng, T. Wu, Y. Li, L. Jiang, W. Deng, K. Han, Combining theory and experiment in the design of a lead-free((CH3NH3)2AgBiI6)double perovskite. New J. Chem. 41,9598–9601(2017). https://doi.org/10.1039/C7NJ0 2365K
86 .Z. Deng, F. Wei, F. Brivio, Y. Wu, S. Sun, P.D. Bristowe,A.K. Cheetham, Synthesis and characterization of the rareearthhybriddoubleperovskites:(CH3NH3)2KGdCl6and(CH3NH3)2KYCl6. J. Phys. Chem. Lett. 8(20), 5015–5020(2017). https://doi.org/10.1021/acs.jpcle tt.7b023 22
87.T.T. Tran, M.A. Quintero, K.E. Arpino, Z.A. Kelly, J.R. Panella, X. Wang, T.M. McQueen, Chemically controlled crystal growth of(CH3NH3)2AgInBr 6. CrystEngComm 20, 5929–5934(2018). https://doi.org/10.1039/C8CE0 0702K
88 .F.Funabiki,Y.Toda,H.Hosono,Opticalandelectrical properties of perovskite variant(CH3NH3)2SnI6. J. Phys.Chem. C 122(20), 10749(2018). https://doi.org/10.1021/acs.jpcc.8b018 20
89 .W. Meng, X. Wang, Z. Xiao, J. Wang, D.B. Mitzi, Y.J. Yan,Parity-forbidden transitions and their impact on the optical absorption properties of lead-free metal halide perovskites and double perovskites. J. Phys. Chem. Lett. 8(13), 2999–3007(2017). https://doi.org/10.1021/acs.jpcle tt.7b010 42
90 .L.Z. Lei, Z.F. Shi, Y. Li, Z.Z. Ma, F. Zhang et al., Highe ciency and air-stable photodetectors based on lead-free double perovskite Cs2AgBiBr 6 thin films. J. Mater. Chem.C 6(30), 7982–7988(2018). https://doi.org/10.1039/C8TC02305K
91 .C. Wu, B. Du, W. Luo, Y. Liu, T. Li et al., Highly e cient and stable self-powered ultraviolet and deep-blue photodetector based on Cs2AgBiBr 6/SnO2 heterojunction. Adv. Optical Mater.(2018). https://doi.org/10.1002/adom.20180 0811
92 .H. Li, X. Shan, J.N. Neu, T. Geske, M. Davis, P. Mao, K.Xiao, T. Siegrist, Z. Yu, Lead-free halide double perovskitepolymer composites for flexible X-ray imaging. J. Mater.Chem. C 6, 11961–11967(2018). https://doi.org/10.1039/C8TC0 1564C
93 .Q. Hu, Z. Deng, M. Hu, A. Zhao, Y. Zhang, Z. Tan, G. Niu,H. Wu, J. Tang, X-ray scintillation in lead-free double perovskite crystals. Sci. China Chem. 61, 1(2018). https://doi.org/10.1007/s1142 6-018-9308-2
94 .J. Luo, X. Wang, S. Li, J. Liu, Y. Guo et al., E cient and stable emission of warm-white light from lead-free halide double perovskites. Nature 563, 541–545(2018). https://doi.org/10.1038/s4158 6-018-0691-0
95 .F.Moser,S.Lyu,LuminescenceinpureandI-doped AgBr crystals. J. Lumin. 3(6), 447–458(1971). https://doi.org/10.1016/0022-2313(71)90025-1
96 .E. Greul, M.L. Petrus, A. Binek, P. Docampo, T. Bein, Highly stable, phase pureCs2AgBiBr6 double perovskite thin films for optoelectronic applications. J. Mater. Chem. A 5(37),19972–19981(2017). https://doi.org/10.1039/C7TA0 6816F
97 .C. Wu, Q. Zhang, Y. Liu, W. Luo, X. Guo et al., The dawn of lead-free perovskite solar cell:highly stable double perovskiteCs2AgBiBr6 film. Adv. Sci. 5(3), 1700759(2018). https://doi.org/10.1002/advs.20170 0759
98.W. Gao, C. Ran, J. Xi, B. Jiao, W. Zhang, M. Wu, X. Hou,Z. Wu, QualityCs2AgBiBr6 double perovskite film for leadfree inverted planar heterojunction solar cells with 2.2%eciency. ChemPhysChem 19(14), 1696–1700(2018). https://doi.org/10.1002/cphc.20180 0346
99 .M. Pantaler, K.T. Cho, V.I.E. Queloz, I.G. Benito, C. Fettkenhauer et al., Hysteresis-free lead-free double perovskite solar cells by interface engineering. ACS Energy Lett. 3(8), 1781–1786(2018). https://doi.org/10.1021/acsen ergyl ett.8b008 71
100 .M. Wang, P. Zeng, S. Bai, J. Gu, F. Li, Z. Yang, M. Liu, Highquality sequential-vapor-depositedCs2Ag Bi Br6 thin films for lead-free perovskite solar cells. Solar RRL(2018). https://doi.org/10.1002/solr.20180 0217
101 .X. Qiu, B. Cao, S. Yuan, X. Chen, Z. Qiu et al., room unstable CsSnI3 to air-stableCs2SnI6:a lead-free perovskite solar cell light absorber with bandgap of 1.48 eV and high absorption coe cient. Sol. Energy Mater. Sol. Cells 159, 227–234(2017). https://doi.org/10.1016/j.solma t.2016.09.022
102 .X. Qiu, Y. Jiang, H. Zhang, Z. Qiu, S. Yuan, P. Wang, B. Cao,Lead-free mesoscopicCs2SnI6 perovskite solar cells using di erent nanostructured ZnO nanorods as electron transport layers. Phys. Status Solidi(RRL)10(8), 587–591(2016).https://doi.org/10.1002/pssr.20160 0166
103 .B. Lee, A. Krenselewski, S.I. Baik, D.N. Seidman, R.P.H.Chang, Solution processing of air-stable molecular semiconducting iodosalts,Cs2SnI6-xBrx, for potential solar cell applications. Sustainable Energy Fuels 1(4), 710–724(2017).https://doi.org/10.1039/C7SE0 0100B
104 .M. Chen, M.G. Ju, A.D. Carl, Y. Zong, R.L. Grimm et al.,Cesium titanium(IV)bromide thin films based stable leadfree perovskite solar cells. Joule 2(3), 558–570(2018). https://doi.org/10.1016/j.joule.2018.01.009
105 .Q.A. Akkerman, M. Gandini, F. Di Stasio, P. Rastogi, F.Palazon et al., Strongly emissive perovskite nanocrystal inks for high-voltage solar cells. Nat. Energy 2(2), 16194(2016).https://doi.org/10.1038/nener gy.2016.194
106 .Z. Liu, B. Sun, X. Liu, J. Han, H. Ye, T. Shi, Z. Tang, G. Liao,E cient carbon-basedCsPbBr3 inorganic perovskite solar cells by using Cu-phthalocyanine as hole transport material.Nano-Micro Lett. 10(2), 34(2018). https://doi.org/10.1007/s4082 0-018-0187-3
107 .Y. Chen, X. Wu, Y. Chu, J. Zhou, B. Zhou, J. Huang, Hybrid field-e ect transistors and photodetectors based on organic semiconductorandCsPbI3perovskitenanorodsbilayer structure. Nano-Micro Lett. 10(4), 57(2018). https://doi.org/10.1007/s4082 0-018-0210-8
2 .H.S. Kim, C.R. Lee, J.H. Im, K.B. Lee, T. Moehl et al., Lead iodide perovskite sensitized all-solid-state submicron thin film mesoscopic solar cell with e ciency exceeding 9%. Sci.Rep. 2, 6022–6025(2012). https://doi.org/10.1038/srep0 0591
3 .H. Zhou, Q. Chen, G. Li, S. Luo, T.B. Song et al., Interface engineering of highly e cient perovskite solar cells. Science345 (6196), 542–546(2014). https://doi.org/10.1126/scien ce.12540 50
4 .N.J. Jeon, J.H. Noh, W.S. Yang, Y.C. Kim, S. Ryu, J. Seo, S.I.Seok, Compositional engineering of perovskite materials for high-performance solar cells. Nature 517, 476–480(2015).https://doi.org/10.1038/natur e1413 3
5 .D.Luo,W.Yang,Z.Wang,A.Sadhanala,Q.Huetal.,Enhanced photovoltage for inverted planar heterojunction perovskite solar cells. Science 360(6396), 1442(2018). https://doi.org/10.1126/scien ce.aap92 82
6 .National Renewable Energy Laboratory(NREL)(2018). https://www.nrel.gov/pv/asset s/pdfs/pv-e c ienci es-chart.20181214 .pdf
7 .M.M. Lee, J. Teuscher, T. Miyasaka, T.N. Murakumi, H.J.Snaith, E cient hybrid solar cells based on meso-superstructured organometal halide perovskites. Science 338(6107),643 –647(2012). https://doi.org/10.1126/scien ce.12286 04
8 .S.D. Stranks, G.E. Eperon, G. Grancini, C. Menelaou, M.J.P.Alcocer, T. Leijtens, L.M. Hertz, A. Petrozza, H.J. Snaith,Electron-holediffusionlengthsexceeding1micrometer inanorganometaltrihalideperovskiteabsorber.Science342 (6156), 341–344(2013). https://doi.org/10.1126/scien ce.12439 82
9 .G.C.Xing,N.Mathews,S.Y.Sun,S.S.Lim,Y.M.Lam,M. Gratzel, S. Mhaisalkar, T.C. Sum, Long-range balanced electron-andhole-transportlengthsinorganic-inorganic CH3NH3PbI3. Science 342(6156), 344–347(2013). https://doi.org/10.1126/scien ce.12431 67
10 .W.S. Yang, B.W. Park, E.H. Jung, N.J. Jeon, Y.C. Kim et al.,Iodide management in formamidinium-lead-halide-based perovskite layers for e cient solar cells. Science 356(6345),1376–1379(2017). https://doi.org/10.1126/scien ce.aan23 01
11 .S.D. Stranks, H.J. Snaith, Metal-halide perovskites for photovoltaic and light-emitting devices. Nat. Nanotech. 10(5),391 –402(2015). https://doi.org/10.1038/nnano.2015.90
12.H. Cho, S.H. Jeong, M.H. Park, Y.H. Kim, C. Wolf, C.L. Lee et al., Overcoming the electroluminescence e ciency limitations of perovskite light-emitting diodes. Science 350(6265),1222–1225(2015). https://doi.org/10.1126/scien ce.aad18 18
13 .H. Zhu, Y. Fu, F. Meng, X. Wu, Z. Gong et al., Lead halide perovskite nanowire lasers with low lasing thresholds and high quality factors. Nat. Mater. 14(6), 636–642(2015). https://doi.org/10.1038/nmat4 271
14 .F. Zhang, B. Yang, K. Zheng, S. Yang, Y. Li, W. Deng, R.He,Formamidiniumleadbromide(FAPbBr3)perovskite microcrystals for sensitive and fast photodetectors. NanoMicro Lett. 10(3), 43(2018). https://doi.org/10.1007/s40820-018-0196-2
15 .L. Chu, R. Hu, W. Liu, Y. Ma, R. Zhang, J. Yang, X. Li,Screen printing large-area organometal halide perovskite thin films for e cient photodetectors. Mater. Res. Bull. 98, 322(2018). https://doi.org/10.1016/j.mater resbu ll.2017.10.039
16 .Q. Chen, J. Wu, X. Ou, B. Huang, J. Almutlaq et al., All-inorganic perovskite nanocrystal scintillators. Nature 561(7721),88 (2018). https://doi.org/10.1038/s4158 6-018-0451-1
17 .H. Luo, X. Lin, X. Hou, L. Pan, S. Huang, X. Chen, E cient and air-stable planar perovskite solar cells formed on grapheneoxide-modified PEDOT:PSS hole transport layer. Nano-Micro Lett. 9(4), 39(2017). https://doi.org/10.1007/s4082
18 .Y. Yang, J. You, Make perovskite solar cells stable. Nature544 (7649), 155(2017). https://doi.org/10.1038/54415 5a
19 .M. Saliba, T. Matsui, K. Domanski, J.Y. Seo, A. Ummadisingu et al., Incorporation of rubidium cations into perovskitesolarcellsimprovesphotovoltaicperformance.Science 354(6309), 5557(2016). https://doi.org/10.1126/scien ce.aah55 57
20 .J.M. Ball, A. Petrozza, Defects in perovskite-halides and their e ects in solar cells. Nat. Energy 1(11), 16149(2016). https://doi.org/10.1038/nener gy.2016.149
21 .J. Cheng, H. Zhang, S. Zhang, D. Ouyang, Z. Huang, M.K.Nazeeruddin, J. Hou, W.C. Choy, Highly e cient planar perovskite solar cells achieved by simultaneous defect engineering and formation kinetic control. J. Mater. Chem. A 6(46),23865(2018). https://doi.org/10.1039/C8TA0 8819E
22 .J.C. Hebig, I. Kühn, J. Flohre, T. Kirchartz, Optoelectronic properties of(CH3NH3)3Sb2I9 thin films for photovoltaic applications. ACS Energy Lett. 1(1), 309–314(2016). https://doi.org/10.1021/acsen ergyl ett.6b001 70
23 .T. Singh, A. Kulkarni, M. Ikegami, T. Miyasaka, E ect of electron transporting layer on bismuth-based lead-free perovskite(CH3NH3)3Bi2I9 for photovoltaic applications. ACS Appl. Mater. Interfaces. 8(23), 14542–14547(2016). https://doi.org/10.1021/acsam i.6b028 43
24 .J. You, L. Meng, T.B. Song, T.F. Guo, Y.M. Yang et al.,Improved air stability of perovskite solar cells via solutionprocessed metal oxide transport layers. Nat. Nanotech. 11(1),75 –81(2016). https://doi.org/10.1038/nnano.2015.230
25 .W. Liao, D. Zhao, Y. Yu, C.R. Grice, C. Wang et al., Leadfree inverted planar formamidinium tin triiodide perovskite solarcellsachievingpowerconversione cienciesupto6.22%. Adv. Mater. 28(42), 9333–9340(2016). https://doi.org/10.1002/adma.20160 2992
26 .H. Tsai, W. Nie, J.C. Blancon, C.C. Stoumpos, R. Asadpour et al., High-e ciency two-dimensional ruddlesden-popper perovskite solar cells. Nature 536(7616), 312–316(2016).https://doi.org/10.1038/natur e1830 6
27 .F. Matteocci, L. Cinà, E. Lamanna, S. Cacovich, G. Divitini,P.A. Midgley, C. Ducati, A.D. Carlo, Encapsulation for longterm stability enhancement of perovskite solar cells. Nano Energy 30, 162–172(2016). https://doi.org/10.1016/j.nanoe n.2016.09.041
28 .G. Flora, D. Gupta, A. Tiwari, Toxicity of lead:a review with recent updates. Interdiscip. Toxicol. 5(2), 47–58(2012). https://doi.org/10.2478/v1010 2-012-0009-2
29 .L.Liang,P.Gao,Lead-freehybridperovskiteabsorbers for viable application:can we eat the cake and have it too.Adv.Sci.5(2),1700331(2018).https://doi.org/10.1002/advs.20170 0331
30 .F. Hao, C.C. Stoumpos, R.P.H. Chang, M.G. Kanatzidis,Anomalous band gap behavior in mixed Sn and Pb perovskites enables broadening of absorption spectrum in solar cells. J. Am. Chem. Soc. 136(22), 8094–8099(2014). https://doi.org/10.1021/ja503 3259
31 .T. Krishnamoorthy, H. Ding, C. Yan, W.L. Leong, T. Baikie et al., Lead-free germanium iodide perovskite materials for photovoltaic applications. J. Mater. Chem. A 3(47), 23829–23832(2015). https://doi.org/10.1039/C5TA0 5741H
32 .H. Wang, H. Zhang, C.C. Chueh, T. Zhao, C. Mao, W. Chen,A.K.Y. Jenac, Enhanced crystallization and performance of formamidinium lead triiodide perovskite solar cells through PbI2-SrCl2 modulation. Mater. Today Energy 7, 239(2018).https://doi.org/10.1016/j.mtene r.2017.10.002
33 .M.T. Klug, A. Osherov, A.A. Haghighirad, S.D. Stranks,P.R. Brown et al., Tailoring metal halide perovskites through metal substitution:influence on photovoltaic and material properties. Energy Environ. Sci. 10(1), 236(2017). https://doi.org/10.1039/C6EE0 3201J
34 .J. Jin, H. Li, C. Chen, B. Zhang, L. Xu, B. Dong, H. Song,Q. Dai, Enhanced performance of perovskite solar cells with zinc chloride additives. ACS Appl. Mater. Interfaces. 9(49),42875–42882(2017). https://doi.org/10.1021/acsam i.7b15310
35.Q. Chen, L. Chen, F.Y. Ye, T. Zhao, F. Tang et al., Ag-incorporated organic-inorganic perovskite films and planar heterojunction solar cells. Nano Lett. 17(5), 3231–3237(2017).https://doi.org/10.1021/acs.nanol ett.7b008 47
36 .J. Zhang, M. Shang, P. Wang, X. Huang, J. Xu, Z. Hu, Y.Zhu,L.Han,n-Typedopingandenergystatestuningin CH3NH3Pb1–xSb2x/3I3 perovskite solar cells. ACS Energy Lett. 1(3), 535–541(2016). https://doi.org/10.1021/acsen ergyl ett.6b002 41
37 .Y. Hu, T. Qiu, F. Bai, X. Miao, S. Zhang, Enhancing moisture-tolerance and photovoltaic performances ofFAPbI3 by bismuth incorporation. J. Mater. Chem. A 5(48), 25258–25265(2017). https://doi.org/10.1039/C7TA0 8824H
38.F. Wei, Z. Deng, S. Sun, F. Xie, G. Kieslich, D.M. Evans,M.A. Carpenter, P.D. Bristowe, A.K. Cheetham, The synthesis,structureandelectronicpropertiesofalead-free hybrid inorganic-organic double perovskite(MA)2KBiCl6(MA=methylammonium).Mater.Horiz.3(4),328–332(2016). https://doi.org/10.1039/C6MH0 0053C
39 .P.D.Matthews,D.J.Lewis,P.O’Brien,Updatingthe road map to metal-halide perovskites for photovoltaics. J.Mater. Chem. A 5(33), 17135–17150(2017). https://doi.org/10.1039/C7TA0 4544A
40 .F. Giustino, H.J. Snaith, Toward lead-free perovskite solar cells. ACS Energy Lett. 1(6), 1233–1240(2016). https://doi.org/10.1021/acsen ergyl ett.6b004 99
41 .K.W.Bagnall,J.B.Laidler,M.A.A.Stewart,Americium chloro-complexes. J. Chem. Soc. A 0, 133–136(1968). https://doi.org/10.1039/J1968 00001 33
42 .L.R. Morss, J. Fuger, Preparation and crystal structures of dicesium berkelium hexachloride and dicesium sodium berkelium hexachloride. Inorg. Chem. 8(7), 1433–1439(1969).https://doi.org/10.1021/ic500 77a01 3
43 .L.R. Morss, M. Siegal, L. Stenger, N. Edelstein, Preparation of cubic chloro complex compounds of trivalent metals:Cs2NaMCl6. Inorg. Chem. 9(7), 1771–1775(1970). https://doi.org/10.1021/ic500 89a03 4
44 .L.R. Morrs, W.R. Robinson, Crystal structure ofCs2Na Bi Cl6.ActaCrystallogr.B28(2),653–654(1972).https://doi.org/10.1107/S0567 74087 20029 48
45 .F. Prokert, K.S. Aleksandrov, Neutron scattering studies on phase transition and phonon dispersion inCs2NaBiCl6. Phys.Status Solidi B 124(2), 503(1984). https://doi.org/10.1002/pssb.22212 40208
46 .W.M.A.Smit,G.J.Dirksen,D.J.Stufkens,Infrared andRamanspectraoftheelpasolitesCs2NaSbCl6and Cs2NaBiCl6:evidenceforapseudoJahn-Tellerdistorted ground state. J. Phys. Chem. Solids 51(2), 189–196(1990).https://doi.org/10.1016/0022-3697(90)90092-T
47 .I.N. Flerov, M.V. Gorev, K.S. Aleksandrov, A. Tressaud, J.Grannec, M. Couzi, Phase transitions in elpasolites(ordered perovskites). Mater. Sci. Eng. 24(3), 81–151(1998). https://doi.org/10.1016/S0927-796X(98)00015-1
48 .E.T.McClure,M.R.Ball,W.Windl,P.M.Woodward,Cs2AgBiX6(X=Br, Cl):new visible light absorbing, leadfree halide perovskite semiconductors. Chem. Mater. 28(5),1348–1354(2016).https://doi.org/10.1021/acs.chemm ater.5b042 31
49 .G. Volonakis, M.R. Filip, A.A. Haghighirad, N. Sakai, B.Wenger, H.J. Snaith, F. Giustino, Lead-free halide double perovskites via heterovalent substitution of noble metals.J. Phys. Chem. Lett. 7(7), 1254–1259(2016). https://doi.org/10.1021/acs.jpcle tt.6b003 76
50 .Y. Bekenstein, J.C. Dahl, J. Huang, W.T. Osowiecki, J.K.Swabeck, E.M. Chan, P. Yang, A.P. Alivisatos, The making and breaking of lead-free double perovskite nanocrystals of cesium silver-bismuth halide compositions. Nano Lett. 18(6), 3502(2018). https://doi.org/10.1021/acs.nanol ett.8b005 60
51.S.E. Creutz, E.N. Crites, M.C. De Siena, D.R. Gamelin, Colloidal nanocrystals of lead-free double-perovskite(elpasolite)semiconductors:synthesis and anion exchange to access new materials. Nano Lett. 18(2), 1118(2018). https://doi.org/10.1021/acs.nanol ett.7b046 59
52 .A.H. Slavney, T. Hu, A.M. Lindenberg, H.I. Karunadasa, A bismuth-halide double perovskite with long carrier recombination lifetime for photovoltaic application. J. Am. Chem.Soc.138(7),2138–2141(2016).https://doi.org/10.1021/jacs.5b132 94
53 .Y. Bi, E.M. Hutter, Y. Fang, Q. Dong, J. Huang, T.J. Savenije,Charge carrier lifetimes exceeding 15μs in methylammonium lead iodide single crystals. J. Phys. Chem. Lett. 7(5), 923–928(2016). https://doi.org/10.1021/acs.jpcle tt.6b002 69
54 .W. Pan, H. Wu, J. Luo, Z. Deng, C. Ge et al., Cs2AgBiBr 6single-crystal X-ray detectors with a low detection limit. Nat.Photonics 11(11), 726–732(2017). https://doi.org/10.1038/s4156 6-017-0012-4
55 .R.L.Z. Hoye, L. Eyre, F. Wei, F. Brivio, A. Sadhanala et al.,Fundamental carrier lifetime exceeding 1μs in Cs2AgBiBr6 double perovskite. Adv. Mater. Interfaces 5(15), 1800464(2018). https://doi.org/10.1002/admi.20180 0464
56 .L. Zhou, Y.F. Xu, B.X. Chen, D.B. Kuang, C.Y. Su, Synthesis and photocatalytic application of stable lead-free Cs2AgBiBr6 perovskite nanocrystals. Small 14(11), 1703762(2018).https://doi.org/10.1002/smll.20170 3762
57 .A.H. Slavney, L. Leppert, D. Bartesaghi, A. Gold-Parker,M.F. Toney, T.J. Savenije, J.B. Neaton, H.I. Karunadasa,Defect-induced band-edge reconstruction of a bismuth-halide double perovskite for visible-light absorption. J. Am. Chem.Soc. 139(14), 5015–5018(2017). https://doi.org/10.1021/jacs.7b016 29
58 .K.Z. Du, W. Meng, X. Wang, Y. Yan, D.B. Mitzi, Bandgapengineeringoflead-freedoubleperovskiteCs2AgBiBr 6 through trivalent metal alloying. Angew. Chem. Int.Ed.56(28),8158–8274(2017).https://doi.org/10.1002/anie.20170 3970
59 .T.T. Tran, J.R. Panella, J.R. Chamorro, J.R. Morey, T.M.McQueen, Designing indirect-direct bandgap transitions in double perovskites. Mater. Horiz. 4(4), 688–693(2017). https://doi.org/10.1039/C7MH0 0239D
60 .G.Volonakis,A.A.Haghighirad,R.L.Milot,W.H.Sio,M.R. Filip et al.,Cs2InAgCl6:a new lead-free halide double perovskite with direct band gap. J. Phys. Chem. Lett. 8(4),772 –778(2017). https://doi.org/10.1021/acs.jpcle tt.6b026 82
61 .J. Luo, S. Li, H. Wu, Y. Zhou, Y. Li et al.,Cs2AgInCl6 double perovskite single crystals:parity forbidden transitions andtheirapplicationforsensitiveandfastUVphotodetectors. ACS Photonics 5(2), 398–405(2017). https://doi.org/10.1021/acsph otoni cs.7b008 37
62 .N. Nandha, A. Nag, Synthesis and luminescence of Mn-doped Cs2Ag In Cl6 double perovskites. Chem. Comm. 54(41), 5205–5208(2018). https://doi.org/10.1039/C8CC0 1982G
63 .K. Tanaka, T. Takahashi, T. Ban, T. Kondo, K. Uchida, N.Miura, Comparative study on the excitons in lead-halidebased perovskite-type crystalsCH3NH3Pb Br3 CH3NH3Pb I3.Solid State Commun. 127(9–10), 619–623(2003). https://doi.org/10.1016/S0038-1098(03)00566-0
64 .C. Zhang, L. Gao, S. Teo, Z. Guo, Z. Xu, S. Zhao, T. Ma,Designofanovelandhighlystablelead-freeCs2NaBiI6double perovskite for photovoltaic application. Sustainable Energy Fuels 2(11), 2419(2018). https://doi.org/10.1039/C8SE0 0154E
65 .X.G. Zhao, J.H. Yang, Y. Fu, D. Yang, Q. Xu, L. Yu, S.H.Wei, L. Zhang, Design of lead-free inorganic halide perovskites for solar cells via cation-transmutation. J. Am. Chem.Soc.139(7),2630–2638(2017).https://doi.org/10.1021/jacs.6b096 45
66 .T. Li, X. Zhao, D. Yang, M.H. Du, L. Zhang, Intrinsic defect properties in halide double perovskites for optoelectronic applications. Phys. Rev. Appl. 10(4), 41001(2018). https://doi.org/10.1103/PhysR evApp lied.10.04100 1
67 .X.G. Zhao, D. Yang, J.C. Ren, Y. Sun, Z. Xiao, L. Zhang,Rational design of halide double perovskites for optoelectronicapplications.Joule2(9),1662(2018).https://doi.org/10.1016/j.joule.2018.06.017
68 .Q. Xu, D. Yang, J. Lv, Y.Y. Sun, L. Zhang, Perovskite solar absorbers:materials by design. Small Methods 2(5), 1700316(2018). https://doi.org/10.1002/smtd.20170 0316
69 .X.G.Zhao,D.Yang,Y.Sun,T.Li,L.Zhang,L.Yu,A.Zunger,Cu-Inhalideperovskitesolarabsorbers.J.Am.Chem.Soc.139(19),6718–6725(2017).https://doi.org/10.1021/jacs.7b021 20
70 .Z.W. Xiao, K.Z. Du, W.W. Meng, J.B. Wang, D.B. Mitzi,Y.F. Yan, Intrinsic instability ofCs2In(I)M(III)X6(M=Bi,Sb; X=Halogen)double perovskites:a combined density functionaltheoryandexperimentalstudy.J.Am.Chem.Soc. 139(17), 6054–6057(2017). https://doi.org/10.1021/jacs.7b022 27
71 .M.G.Brik,I.V.Kityk,Modelingoflatticeconstantand their relations with ionic radii and electronegativity of constituting ions ofA2XY6 cubic crystals(A=K, Cs, Rb, Tl;X=tetravalent cation, Y=F, Cl, Br, I). J. Phys. Chem. Solids72(11),1256–1260(2011).https://doi.org/10.1016/j.jpcs.2011.07.016
72 .A.E. Maughan, A.M. Ganose, M.M. Bordelon, E.M. Miller,D.O. Scanlon, J.R. Neilson, Defect tolerance to intolerance in the vacancy-ordered double perovskite semiconductors Cs2Sn I6 andCs2Te I6. J. Am. Chem. Soc. 138(27), 8453–8464(2016). https://doi.org/10.1021/jacs.6b032 07
73 .A.E. Maughan, A.M. Ganose, A.M. Candia, J.T. Granger,D.O. Scanlon, J.R. Neilson, Anharmonicity and octahedral tilting in hybrid vacancy-ordered double perovskites. Chem.Mater. 30(2), 472–482(2018). https://doi.org/10.1021/acs.chemm ater.7b045 16
74 .B. Lee, C.C. Stoumpos, N. Zhou, F. Hao, C. Malliakas, C.Y.Yeh, T.J. Marks, M.G. Kanatzidis, R.P.H. Chang, Air-stable molecularsemiconductingiodosaltsforsolarcellapplications:Cs2SnI6 as a hole conductor. J. Am. Chem. Soc.136 (43), 15379–15385(2014). https://doi.org/10.1021/ja508464 w
75.S. Ghosh, S. Paul, S.K. De, Control synthesis of air-stable morphology tunable Pb-freeCs2Sn I6 perovskite nanoparticles and their photodetection properties. Part. Part. Syst. Char.35 (9), 1800199(2018). https://doi.org/10.1002/ppsc.201800199
76 .A. Wang, X. Yan, M. Zhang, S. Sun, M. Yang, W. Shen, X.Pan, P. Wang, Z. Deng, Controlled synthesis of lead-free and stable perovskite derivativeCs2SnI6 nanocrystals via a facile hot-injection process. Chem. Mater. 28(22), 8132–8140(2016). https://doi.org/10.1021/acs.chemm ater.6b013 29
77 .Z. Tan, J. Li, C. Zhang, Z. Li, Q. Hu et al., Highly e cient blue-emitting Bi-doped Cs2SnCl6 perovskite variant:photoluminescence induced by impurity doping. Adv. Funct.Mater.28(29),1801131(2018).https://doi.org/10.1002/adfm.20180 1131
78 .N. Sakai, A.A. Haghighirad, M.R. Filip, P.K. Nayak, S. Nayak et al., Solution-processed cesium hexabromopalladate(IV),Cs2PdBr 6, for optoelectronic applications. J. Am. Chem.Soc. 139(17), 6030–6033(2017). https://doi.org/10.1021/jacs.6b132 58
79 .L. Zhou, J.F. Liao, Z.G. Huang, X.D. Wang, Y.F. Xu, H.Y.Chen, D.B. Kuang, C.Y. Su, All-inorganic lead-freeCs2Pd X6(X=Br, I)perovskite nanocrystals with single unit cell thickness and high stability. ACS Energy Lett. 3(10), 2613–2619(2018). https://doi.org/10.1021/acsen ergyl ett.8b017 70
80 .K.F. Guenther, The preparation of some alkali hexabromotitanates(IV). Inorg. Chem. 3(12), 1788–1789(1964). https://doi.org/10.1021/ic500 22a03 3
81 .M.G. Ju, M. Chen, Y. Zhou, H.F. Garces, J. Dai et al., Earthabundant nontoxic titanium(IV)-based vacancy-ordered double perovskite halides with tunable 1.0 to 1.8 eV bandgaps for photovoltaic applications. ACS Energy Lett. 3(2), 297–304(2018). https://doi.org/10.1021/acsen ergyl ett.7b011 67
82 .Z. Deng, F. Wei, S. Sun, G. Kieslich, A.K. Cheetham, P.D.Bristowe, Exploring the properties of lead-free hybrid double perovskites using a combined computational-experimental approach. J. Mater. Chem. A 4(31), 12025–12029(2016).https://doi.org/10.1039/C6TA0 5817E
83 .F.X. Wei, Z.Y. Deng, S.J. Sun, F.H. Zhang, D.M. Evans et al.,Synthesis and properties of a lead-free hybrid double perovskite:(CH3NH3)2AgBiBr 6. Chem. Mater. 29(3), 1089–1094(2017). https://doi.org/10.1021/acs.chemm ater.6b039 44
84 .Y.J. Li, T. Wu, L. Sun, R.X. Yang, L. Jiang et al., Leadfreeandstableantimony-silver-halidedoubleperovskite(CH3NH3)2AgSbI6. RSC Adv. 7(56), 3517–35180(2017).https://doi.org/10.1039/C7RA0 6130G
85 .P. Cheng, T. Wu, Y. Li, L. Jiang, W. Deng, K. Han, Combining theory and experiment in the design of a lead-free((CH3NH3)2AgBiI6)double perovskite. New J. Chem. 41,9598–9601(2017). https://doi.org/10.1039/C7NJ0 2365K
86 .Z. Deng, F. Wei, F. Brivio, Y. Wu, S. Sun, P.D. Bristowe,A.K. Cheetham, Synthesis and characterization of the rareearthhybriddoubleperovskites:(CH3NH3)2KGdCl6and(CH3NH3)2KYCl6. J. Phys. Chem. Lett. 8(20), 5015–5020(2017). https://doi.org/10.1021/acs.jpcle tt.7b023 22
87.T.T. Tran, M.A. Quintero, K.E. Arpino, Z.A. Kelly, J.R. Panella, X. Wang, T.M. McQueen, Chemically controlled crystal growth of(CH3NH3)2AgInBr 6. CrystEngComm 20, 5929–5934(2018). https://doi.org/10.1039/C8CE0 0702K
88 .F.Funabiki,Y.Toda,H.Hosono,Opticalandelectrical properties of perovskite variant(CH3NH3)2SnI6. J. Phys.Chem. C 122(20), 10749(2018). https://doi.org/10.1021/acs.jpcc.8b018 20
89 .W. Meng, X. Wang, Z. Xiao, J. Wang, D.B. Mitzi, Y.J. Yan,Parity-forbidden transitions and their impact on the optical absorption properties of lead-free metal halide perovskites and double perovskites. J. Phys. Chem. Lett. 8(13), 2999–3007(2017). https://doi.org/10.1021/acs.jpcle tt.7b010 42
90 .L.Z. Lei, Z.F. Shi, Y. Li, Z.Z. Ma, F. Zhang et al., Highe ciency and air-stable photodetectors based on lead-free double perovskite Cs2AgBiBr 6 thin films. J. Mater. Chem.C 6(30), 7982–7988(2018). https://doi.org/10.1039/C8TC02305K
91 .C. Wu, B. Du, W. Luo, Y. Liu, T. Li et al., Highly e cient and stable self-powered ultraviolet and deep-blue photodetector based on Cs2AgBiBr 6/SnO2 heterojunction. Adv. Optical Mater.(2018). https://doi.org/10.1002/adom.20180 0811
92 .H. Li, X. Shan, J.N. Neu, T. Geske, M. Davis, P. Mao, K.Xiao, T. Siegrist, Z. Yu, Lead-free halide double perovskitepolymer composites for flexible X-ray imaging. J. Mater.Chem. C 6, 11961–11967(2018). https://doi.org/10.1039/C8TC0 1564C
93 .Q. Hu, Z. Deng, M. Hu, A. Zhao, Y. Zhang, Z. Tan, G. Niu,H. Wu, J. Tang, X-ray scintillation in lead-free double perovskite crystals. Sci. China Chem. 61, 1(2018). https://doi.org/10.1007/s1142 6-018-9308-2
94 .J. Luo, X. Wang, S. Li, J. Liu, Y. Guo et al., E cient and stable emission of warm-white light from lead-free halide double perovskites. Nature 563, 541–545(2018). https://doi.org/10.1038/s4158 6-018-0691-0
95 .F.Moser,S.Lyu,LuminescenceinpureandI-doped AgBr crystals. J. Lumin. 3(6), 447–458(1971). https://doi.org/10.1016/0022-2313(71)90025-1
96 .E. Greul, M.L. Petrus, A. Binek, P. Docampo, T. Bein, Highly stable, phase pureCs2AgBiBr6 double perovskite thin films for optoelectronic applications. J. Mater. Chem. A 5(37),19972–19981(2017). https://doi.org/10.1039/C7TA0 6816F
97 .C. Wu, Q. Zhang, Y. Liu, W. Luo, X. Guo et al., The dawn of lead-free perovskite solar cell:highly stable double perovskiteCs2AgBiBr6 film. Adv. Sci. 5(3), 1700759(2018). https://doi.org/10.1002/advs.20170 0759
98.W. Gao, C. Ran, J. Xi, B. Jiao, W. Zhang, M. Wu, X. Hou,Z. Wu, QualityCs2AgBiBr6 double perovskite film for leadfree inverted planar heterojunction solar cells with 2.2%eciency. ChemPhysChem 19(14), 1696–1700(2018). https://doi.org/10.1002/cphc.20180 0346
99 .M. Pantaler, K.T. Cho, V.I.E. Queloz, I.G. Benito, C. Fettkenhauer et al., Hysteresis-free lead-free double perovskite solar cells by interface engineering. ACS Energy Lett. 3(8), 1781–1786(2018). https://doi.org/10.1021/acsen ergyl ett.8b008 71
100 .M. Wang, P. Zeng, S. Bai, J. Gu, F. Li, Z. Yang, M. Liu, Highquality sequential-vapor-depositedCs2Ag Bi Br6 thin films for lead-free perovskite solar cells. Solar RRL(2018). https://doi.org/10.1002/solr.20180 0217
101 .X. Qiu, B. Cao, S. Yuan, X. Chen, Z. Qiu et al., room unstable CsSnI3 to air-stableCs2SnI6:a lead-free perovskite solar cell light absorber with bandgap of 1.48 eV and high absorption coe cient. Sol. Energy Mater. Sol. Cells 159, 227–234(2017). https://doi.org/10.1016/j.solma t.2016.09.022
102 .X. Qiu, Y. Jiang, H. Zhang, Z. Qiu, S. Yuan, P. Wang, B. Cao,Lead-free mesoscopicCs2SnI6 perovskite solar cells using di erent nanostructured ZnO nanorods as electron transport layers. Phys. Status Solidi(RRL)10(8), 587–591(2016).https://doi.org/10.1002/pssr.20160 0166
103 .B. Lee, A. Krenselewski, S.I. Baik, D.N. Seidman, R.P.H.Chang, Solution processing of air-stable molecular semiconducting iodosalts,Cs2SnI6-xBrx, for potential solar cell applications. Sustainable Energy Fuels 1(4), 710–724(2017).https://doi.org/10.1039/C7SE0 0100B
104 .M. Chen, M.G. Ju, A.D. Carl, Y. Zong, R.L. Grimm et al.,Cesium titanium(IV)bromide thin films based stable leadfree perovskite solar cells. Joule 2(3), 558–570(2018). https://doi.org/10.1016/j.joule.2018.01.009
105 .Q.A. Akkerman, M. Gandini, F. Di Stasio, P. Rastogi, F.Palazon et al., Strongly emissive perovskite nanocrystal inks for high-voltage solar cells. Nat. Energy 2(2), 16194(2016).https://doi.org/10.1038/nener gy.2016.194
106 .Z. Liu, B. Sun, X. Liu, J. Han, H. Ye, T. Shi, Z. Tang, G. Liao,E cient carbon-basedCsPbBr3 inorganic perovskite solar cells by using Cu-phthalocyanine as hole transport material.Nano-Micro Lett. 10(2), 34(2018). https://doi.org/10.1007/s4082 0-018-0187-3
107 .Y. Chen, X. Wu, Y. Chu, J. Zhou, B. Zhou, J. Huang, Hybrid field-e ect transistors and photodetectors based on organic semiconductorandCsPbI3perovskitenanorodsbilayer structure. Nano-Micro Lett. 10(4), 57(2018). https://doi.org/10.1007/s4082 0-018-0210-8