Intensifying Chelation of Pb-Related Defects for Enhancing Stability in Halide Perovskite Thin-Film Solar Cells

Abstract

Halide perovskite-based thin-film solar cells have achieved remarkable power conversion efficiency, yet stability issues linked to Pb-related defects pose significant challenges. These defects, predominantly forming during film fabrication, particularly at surfaces and grain boundaries, create nonradiative recombination centers that also accelerate device degradation. To mitigate these defects, a chelation-based passivation strategy is introduced, particularly through antisolvent additive engineering. A range of natural organic chelating agents, including adipic acid, malic acid, tartaric acid, and citric acid, is employed to passivate Pb-related defects by forming polydentate bonds with uncoordinated Pb2+ ions at surfaces and grain boundaries. This chelation-based passivation strategy effectively reduces nonradiative recombination and improves interfacial charge extraction. Notably, perovskite solar cells treated with citric acid demonstrate an increase in power conversion efficiency from 20.7% to 22.0%, along with sustained stability, maintaining over 90% of their initial efficiency after 150 h of operation under continuous illumination in ambient air without any encapsulation, highlighting the potential of environmentally friendly chelating agents in improving the performance and stability of perovskite solar cells.