Journal
ORGANIC ELECTRONICS
Volume 78, Issue -, Pages -Publisher
ELSEVIER
DOI: 10.1016/j.orgel.2019.105573
Keywords
Benzoimidazole; Electron transport layer; Inverted perovskite solar cell; Passivation effect; Iodine ions diffusion
Funding
- Natural Science Foundation of China [51372158, 51772195, 61705150]
- Six Talent Peaks Project in Jiangsu Province
- Natural Science Foundation of Jiangsu Province [BK20160325]
- Suzhou Key Laboratory for Advanced Carbon Materials and Wearable Energy Technologies
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Although [6,6] -phenyl-C-61-butyric acid methyl ester (PC61BM) has been widely used as electron transport layer (ETL) for inverted perovskite solar cells (PeSCs), it still remains to be improved. Herein, we report that amphoteric imidazole (IZ) and benzimidazole (BIZ) can act as effective and multifunctional dopants for PC61BM-based ETL. The resultant MAPbI(3)-xCl(3) -based PeSCs outperform the devices with pristine PC61BM ETL with power conversion efficiency (PCE) significantly improved from 14.38% to 15.62/16.47%. Detailed mechanism studies demonstrate that IZ and BIZ-doping cause remarkable reduction of ETL surface roughness and significant increase in electrical conductivity of ETL, both of which facilitate the electron transport from pemvskite (PVK) and Ag cathode. More importantly, IZ and BIZ as dopants may passivate both Lewis-acid and Lewis-base type defects on the PVK surface due to their amphoteric nature. DFT computations further reveal that BIZ is a better Lewisbase and Lewis-acid than IZ due to its larger pi-conjugation, which thus makes it a superior dopant over IZ. In addition, the PeSCs with PC61BM:BIZ based ETL display enhanced device stability by retarding the I- anion migration from PVK to Ag cathode.
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