Bottom-up holistic carrier management strategy induced synergistically by multiple chemical bonds to minimize energy losses for efficient and stable perovskite solar cells

The defects from electron transport layer, perovskite layer and their interface would result in carrier nonradiative recombination losses. Poor buried interfacial contact is detrimental to charge extraction and device stability. Here, we report a bottom-up holistic carrier management strategy induced synergistically by multiple chemical bonds to minimize bulk and interfacial energy losses for high-performance perovskite photovoltaics. 4-trifluoromethyl-benzamidine hydrochloride (TBHCI) containing -CF3, amidine cation and Cl is in advance incorporated into SnO2 colloid solution to realize bottom-up modification. The synergistic effect of multiple functional groups and multiple-bond-induced chemical interaction are revealed theoretically and experimentally. F and Cl can passivate oxygen vacancy and/or undercoordinated Sn4+ defects by coordinating with Sn4+. The F can suppress cation migration and modulate crystallization via hydrogen bond with FA(+), and can passivate lead defects by coordinating with Pb2+. The - NH2-C=NH2+ and Cl can passivate cation and anion vacancy defects through ionic bonds with perovskites, respectively. Through TBHCI modification, the suppression of agglomeration of SnO2 nanopartides, bulk and interfacial defect passivation, and release of tensile strains of perovskite films are demonstrated, which resulted in a PCE enhancement from 21.28% to 23.40% and improved stability. With post-treatment, the efficiency is further improved to 23.63%. (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

A bottom-up holistic carrier management strategy is proposed in this study to minimize bulk and interfacial energy losses for high-performance perovskite photovoltaics, induced synergistically by multiple chemical bonds.