Mechanism for Broadband White-Light Emission from Two-Dimensional (110) Hybrid Perovskites
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- 作者：Te Hu ; Matthew D. Smith ; Emma R. Dohner ; Meng-Ju Sher ; Xiaoxi Wu ; M. Tuan Trinh ; Alan Fisher ; Jeff Corbett ; X.-Y. Zhu ; Hemamala I. Karunadasa ; Aaron M. Lindenberg
- 刊名：The Journal of Physical Chemistry Letters
- 出版年：2016
- 出版时间：June 16, 2016
- 年：2016
- 卷：7
- 期：12
- 页码：2258-2263
- 全文大小：386K
- 年卷期：0
- ISSN：1948-7185
文摘
The recently discovered phenomenon of broadband white-light emission at room temperature in the (110) two-dimensional organic–inorganic perovskite (N-MEDA)[PbBr4] (N-MEDA = N1-methylethane-1,2-diammonium) is promising for applications in solid-state lighting. However, the spectral broadening mechanism and, in particular, the processes and dynamics associated with the emissive species are still unclear. Herein, we apply a suite of ultrafast spectroscopic probes to measure the primary events directly following photoexcitation, which allows us to resolve the evolution of light-induced emissive states associated with white-light emission at femtosecond resolution. Terahertz spectra show fast free carrier trapping and transient absorption spectra show the formation of self-trapped excitons on femtosecond time-scales. Emission-wavelength-dependent dynamics of the self-trapped exciton luminescence are observed, indicative of an energy distribution of photogenerated emissive states in the perovskite. Our results are consistent with photogenerated carriers self-trapped in a deformable lattice due to strong electron–phonon coupling, where permanent lattice defects and correlated self-trapped states lend further inhomogeneity to the excited-state potential energy surface.