Multidentate chelation via pyridine-based molecules for high-efficiency perovskite solar cells

Abstract

The non-radiative recombination loss at the interface between a perovskite layer and hole transport layer is one of the main sources of energy loss in perovskite solar cells (PSCs). Non-radiative recombination caused by surface defects greatly limits further improvement of power conversion efficiency (PCE). Interfacial passivation is one of the commonly used methods to improve PCE, but traditional passivation methods often involve single-point coordination, and their passivation effect is limited. In this study, we used a multi-site binding passivation method, introducing diethyl 2,6-pyridinedicarboxylate (DIP) as a passivation layer at the interface between the perovskite and the hole transport layer. The ester and pyridinium groups can interact effectively with uncoordinated Pb²⁺, and this multidentate chelation effect can repair various defects, improve crystallization, and promote interfacial carrier transfer. As a result, the optimized device achieves an efficiency of 23.68%. Additionally, due to the hydrophobicity of DIP, the device exhibits excellent humidity stability, maintaining 89.40% of its initial PCE after 550 hours at a relative humidity of 65 ± 5%.