Unveiling the key factor affecting the illumination deterioration and response measures for lead halide perovskite solar cells

So far, it's been widely acknowledged that the PbI2 decomposition under illumination mainly accounts for the degradation of perovskite solar cells (PSCs) under maximum power point (MPP) tracking condition. However, PSCs without excess PbI2 were also reported to deteriorate rapidly under the same condition. Here, we demonstrate that the key to enhance PSCs stability under MPP tracking condition is not to have fascinating surface morphology with effective suppression of nonradiative recombination traps but to prevent the migration of iodine ion (I-) under light illumination. By partially substituting methylammonium chloride (MACl) with methylammonium iodide (MAI) and simutaneouly introducing I2 during the sequential deposition, the iodine vacancies in perovskite films are substantially suppressed, thereby lim-iting the pathways for I migration. As a consequence, PSCs with efficiency of 24.28% are fabricated with remarkably enhanced working stability. (C) 2022 Science Press and Dalian Institute of Chemical Physics, Chinese Academy of Sciences. Published by ELSEVIER B.V. and Science Press. All rights reserved.

Automated summary

The key to enhancing the stability of perovskite solar cells under maximum power point tracking condition is found to be preventing the migration of iodine ions under light illumination, rather than optimizing the surface morphology. By making modifications to the deposition process, PSCs with significantly improved working stability have been successfully fabricated.