Integration of SWCNT and WO3 for efficient charge extraction in all-inorganic perovskite solar cells

The construction of efficient interfacial charge transfer and extraction plays an essential role in improving the photovoltaic performance of perovskite solar cells (PSCs). Herein, the single-walled carbon nanotube (SWCNT) and WO3 are integrated as a robust hole extractor for all-inorganic CsPbBr3 PSCs. The introduction of SWCNT with high carrier transport behavior and numerous oxygen-containing edge groups not only promotes the hole transport from CsPbBr3 film to carbon back electrode, but also passivates the metal ion defect states within the CsPbBr3 film. The further integration of WO3 hole transport materials compensates for the energy level gap between the perovskite film and the carbon electrode to decrease interfacial energy loss and boosts hole extraction. Benefiting from the collaborative promotion of charge transport and extraction by SWCNT and WO3, the tailored CsPbBr3 PSCs without encapsulation achieve a champion power conversion efficiency of 10.47 % and a long-term stability with 91.3 % retention of the initial efficiency under high temperature and humidity conditions for 800 h.