Affiliation:
1. Hunan Key Laboratory of Super‐microstructure and Ultrafast Process Hunan Key Laboratory of Nanophotonics and Devices Institute of Super‐microstructure and Ultrafast Process in Advanced Materials (ISUPAM) School of Physics and Electronics Central South University Changsha Hunan 410083 P. R. China
2. State Key Laboratory of Powder Metallurgy Powder Metallurgy Research Institute Central South University Changsha Hunan 410083 P. R. China
3. Michael Grätzel Center for Mesoscopic Solar Cells Wuhan National Laboratory for Optoelectronics Huazhong University of Science and Technology Wuhan Hubei 430074 P. R. China
4. Department of Physics and Astronomy University of Rochester Rochester New York NY 14627 USA
Abstract
AbstractFast reaction between organic salt and lead iodide always leads to small perovskite crystallites and concentrated defects. Here, polyacrylic acid is blended with organic salt, so as to regulate the crystallization in a two‐step growth method. It is observed that addition of polyacrylic acid retards aggregation and crystallization behavior of the organic salt, and slows down the reaction rate between organic salt and PbI2, by which “slow‐release effect” is defined. Such effect improves crystallization of perovskite. X‐ray diffraction study shows that, after addition of 2 mm polyacrylic acid, average crystallite size of perovskite increases from ≈40 to ≈90 nm, meanwhile, grain size increases. Thermal admittance spectroscopy study shows that trap density is reduced by nearly one order (especially for deep energy levels). Due to the improved crystallization and reduced trap density, charge recombination is obviously reduced, while lifetime of charge carriers in perovskite film and devices are prolonged, according to time‐resolved photoluminescence and transient photo‐voltage decay curve tests, respectively. Accordingly, power conversion efficiency of the device is promoted from 19.96 (±0.41)% to 21.84 (±0.25)% (with a champion efficiency of 22.31%), and further elevated to 24.19% after surface modification by octylammonium iodide.
Funder
National Natural Science Foundation of China
Subject
General Materials Science,General Chemistry
Cited by
8 articles.
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