Phase homogeneity mediated charge-carrier balance in two-step-method halide perovskite photovoltaics

• Published in: Energy & environmental science Vol. 18; no. 3; pp. 131 - 1319
• Main Authors: Qu, Duo, Shang, Chuanzhen, Yang, Xiaoyu, Wang, Chenyun, Zhou, Bin, Qin, Qichao, Gao, Lei, Qiao, Jingyuan, Guo, Qiang, Yang, Wenqiang, Wang, Kai, Zhu, Rui, Tu, Yongguang, Huang, Wei
• Format: Journal Article
• Language: English
• Published: Cambridge Royal Society of Chemistry 04.02.2025
• Subjects: Ammonium; Ammonium chloride; Charge efficiency; Chloride transport; Crystallites; Crystals; Current carriers; Energy conversion efficiency; Heterogeneity; Homogeneity; Integrity; Perovskites; Photovoltaic cells; Photovoltaics; Physicochemical properties; Semiconductors; Solar cells; Structural stability
• DOI: 10.1039/d4ee04419c
• ISSN: 1754-5692

The multi-scale chemical phase heterogeneity of halide perovskites seriously affects the physical functional integrity of semiconductors and the performance of photovoltaic devices. However, the phase homogeneity in two-step-method perovskites (TSPs) has rarely been investigated. Here, we elaborate on the severe heterogeneity of the FAMA-based TSP film and found that residual PbI 2 crystallites and Pb 0 species accumulate at the top while a Cl/MA-rich interface is present at the bottom, impeding carrier nonequilibrium transport in the vertical direction. The homogeneity of the TSP film is reinforced by chemical tailoring with 4-methoxyphenethyl ammonium chloride, thus achieving superior structural stability and a charge carrier balance dynamic process. The target TSP p-i-n device achieves a recorded power conversion efficiency of 25.12% under 1-sun illumination (certified at 24.01%). This study uncovers the hidden physicochemical properties of the TSP film, guiding the understanding of microscopic homogeneity and functional integrity and the design of efficient two-step-method inverted perovskite solar cells. Phase homogeneity mediated charge-carrier balance reveals the heterogeneity issue of two-step-method perovskite films.