Highly Enhanced Efficiency of Planar Perovskite Solar Cells by an Electron Transport Layer Using Phytic Acid–Complexed SnO<sub>2</sub> Colloids
Congcong Liu, Haijun Su, Keyu Xie, Hongqiang Wang, Peng Zhai, Ninghui Chang, Shan Zhang, Qingfu Ban, Min Guo, Jun Zhang, Lin Liu
Abstract
SnO 2 aqueous colloids as electron transport layers (ETLs) have been widely employed in planar perovskite solar cells (PSCs). However, the surface defects and energy level mismatch at the SnO 2 ETL/perovskite interface are still great challenges for the power conversion efficiency (PCE) improvement. Herein, a natural and nontoxic phytic acid (PA) compound is introduced into the SnO 2 aqueous colloids to prepare the ETL to depress its defects, and systematically study the influence of different PA complexation on the photovoltaic performance of PSCs. The results demonstrate that PA complexation can assemble unique coordination complexes between PA and SnO 2 nanocrystals (NCs) in a new bonding of SnOP, which can passivate SnO 2 inherent surface defects and tune the electronic properties of SnO 2 ETLs. PA complexation can significantly disaggregate the SnO 2 oligomers and reduce the cluster size distribution from 98.37 to 15.87 nm. Meanwhile, the reduction of surface trap states inhibits the potential barriers, thus the electrical conductivity is about two times as high as compared with the pristine SnO 2 ETLs. Consequently, a high PCE of 21.43% in PA‐SnO 2 ‐based PSCs is obtained, which presents an improvement of 10.9% over that of the pristine SnO 2 ‐based PSCs.