Efficient Grain Boundary Suture by Low-Cost Tetra-ammonium Zinc Phthalocyanine for Stable Perovskite Solar Cells with Expanded Photoresponse

Defects within the grain boundaries (GBs) of halide perovskite films make fabrication of efficient and stable perovskite solar cells (PSCs) highly challenging. Here, a low-cost tetra-ammonium zinc phthalocyanine (ZnPc) was used to post-treat the MAPbI₃ (MA = CH₃NH₃) film. Two-dimensional (ZnPc)_0.5MA _n-1Pb _nI_{3 n+1} was successfully constructed within the GBs of MAPbI₃ film achieving a GBs suture for passivating the defects in GBs. Time-resolved photoluminescence showed that the modification increased the decay time from 44 to 57 ns indicating the passivation of GBs reduces trap-assisted recombination. The PSCs with modified perovskite exhibited increased photovoltage, and the best efficiency was improved up to 20.3%. More importantly, the long-term stability of the responding PSCs against humidity and heating was further improved unprecedentedly. Moreover, the modified MAPbI₃ films revealed a self-repairing capability under mild heating. This work provided a novel insight into ongoing fabrication of efficient and stable PSCs by the efficient GBs suture with low-cost phthalocyanine.