An efficient and hydrophobic molecular doping in perovskite solar cells

Highlights: • A novel dopant fluorinated iron(III) porphine (Fe(III)-PP) has been developed for PTAA in PSCs. • Fe(III)-PP has excellent doping performance, high migration barrier and hydrophobic nature. • PSCs based on Fe(III)-PP doped PTAA show a champion efficiency as high as 21.73%. • PSCs exhibit superior long-term stability up to 1200 h under air exposure without encapsulation. Longevity has been a long-standing challenge for perovskite photovoltaics. In general, Li-TFSI/t-BP are the state-of-the-art bi-dopants for the hole-transporting layer (HTL) in perovskite solar cells (PSCs), although such dopants significantly diminish the stability of devices. Here, we reported a novel dopant of fluorinated iron(III) porphine (Fe(III)-PP) as a potential alternative to the Li-TFSI/t-BP. The optimized PSCs exhibit a champion power conversion efficiency (PCE) of 21.73%, which outperforms the standard bi-dopants Li-TFSI/t-BP (21.07%). The high migration barrier together with the hydrophobic nature of the Fe(III)-PP, which in turn suppress intrinsic ion migration and alleviate extrinsic moisture-induced degradation, resulting in prominent improvement of long-term stability of PSCs up to 1200 h under air exposure without encapsulation.