Highly stable and Efficient Perovskite Solar Cells Based on FAMA-Perovskite-Cu:NiO Composites with 20.7% Efficiency and 80.5% Fill Factor

To solve critical issues related to device stability and performance of perovskite solar cells (PSCs), FA(0.026)MA(0.974)PbI(3-)(y)Cl(y)-Cu:NiO (formamidinium methylammonium (FAMA)-perovskite-Cu:NiO) and Al2O3/Cu:NiO composites are developed and utilized for fabrication of highly stable and efficient PSCs through fully-ambient-air processes. The FAMA-perovskite-Cu:NiO composite crystals prepared without using any antisolvents not only improve the perovskite film quality with large-size crystals and less grain boundaries but also tailor optical and electronic properties and suppress charge recombination with reduction of trap density. A champion device based on the composites as light absorber and Al2O3/Cu:NiO interfacial layer between electron transport layer and active layer yields power conversion efficiency (PCE) of 20.67% with V-OC of 1.047 V, J(SC) of 24.51 mA cm(-2), and fill factor of 80.54%. More importantly, such composite-based PSCs without encapsulation show significant enhancement in long-term air-stability, thermal- and photostability with retaining 97% of PCE over 240 d under ambient conditions (25-30 degrees C, 45-55% humidity).