Achieving a high-quality active film through surface passivation to enhance the stability of inverted perovskite solar cells

Abstract

Non-radiative recombination induced by the defects on the surfaces of perovskite films significantly impedes the enhancement of performance in perovskite solar cells (PSCs). Therefore, modifying the surface of perovskite films is crucial for achieving high-efficiency PSCs. In this study, we propose a surface passivation method for perovskite films using cyanomethyltriphenylphosphonium chloride (CTPC) molecules. Our observations reveal that the CN group in CTPC molecules can bond with Pb²⁺ to passivate the undercoordinated lead sites on the perovskite layer. Additionally, the positively charged P⁺ moiety of CTPC molecules can interact electrostatically with I⁻ ions, further reducing defect density. Consequently, a remarkable power conversion efficiency (PCE) of 24.63% was obtained. And the encapsulated device retained 88% of its initial PCE over a period of 1200 hours. This scholarly endeavor elucidates a novel methodology for mitigating interfacial defects and thereby propelling advancements in high-performance planar PSCs.