An Insight into the Potential of Random Poly(heteroarylene鈥搗inylene)s as Donor Materials in Bulk Heterojunction Solar Cells

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• 作者：Roberto Grisorio ; Giovanni Allegretta ; Giuseppe Romanazzi ; Gian Paolo Suranna ; Piero Mastrorilli ; Marco Mazzeo ; Miriam Cezza ; Sonia Carallo ; Giuseppe Gigli
• 刊名：Macromolecules
• 出版年：2012
• 出版时间：August 28, 2012
• 年：2012
• 卷：45
• 期：16
• 页码：6396-6404
• 全文大小：466K
• 年卷期：v.45,no.16(August 28, 2012)
• ISSN：1520-5835

文摘

The manuscript describes the design, preparation and characterization of two structurally isomeric random poly(arylene鈥搗inylene)s, the properties of which have been optimized for their use as donor materials in BHJ solar cells. The structure of the polymers was aimed at broadening as much as possible their absorption profile. Poly[9,9-dioctylfluorene鈥搗inylene-co-4,7-dithiophen-2-yl-benzo[1,2,5]thiadiazole鈥搗inylene] (P1) and poly[2,7-dithiophen-2-yl-9,9-dioctylfluorene鈥搗inylene-co-4,7-benzo[1,2,5]thiadiazole鈥搗inylene] (P2) were prepared using the Suzuki鈥揌eck polymerization. The polymers were characterized by elemental analysis, NMR, UV鈥搗is absorption and photoluminescence, cyclic voltammetry, and GPC. The electrochemical characterization of P1 and P2 revealed similar HOMO/LUMO energy levels, although the UV鈥搗is absorption profile of P2 is markedly broader than the one exhibited by P1. The more panchromatic absorption of P2 was explained by DFT and TDDFT calculations showing that the model systems, contributing together to the description of the random polymeric structure, exhibited different calculated excitation energies, that cover a broader portion of the absorption spectrum. In BHJ solar cells, the broadness of the absorption strongly influences the BHJ solar cell performances of P2 compared to P1 leading to higher short circuit currents and to a 3-fold higher power conversion efficiency. The PCE value (0.6%) obtained with P2 is in line with those obtained for other poly(heteroarylene鈥搗inylene)s donors and is amenable to improvement by optimizing the device construction (PC₆₁BM amount in the blend or use of annealing processes). These results demonstrate how combination of a suitable choice of the sequence of aryl units together with the potentialities offered by random polymers, can be useful tools in the design of new light-harvesting polymers in BHJ.