Bipolar metal oxide charge transporting layers for efficient perovskite solar cells

Metal oxide materials are crucial for efficient perovskite solar cells (PSCs) due to their stability and wide bandgap. We introduce a low-temperature intercalation method using p-type nickel oxide (NiO) with cesium carbonate (Cs2CO3) to enable bipolar charge transport in PSCs. The Cs2CO3-intercalated NiO serves as both hole and electron transport layers in inverted and conventional planar PSCs, enhancing electron extraction without compromising hole extraction efficiency. This approach achieves power conversion efficiencies of up to 12.08% and 13.98% for inverted and conventional planar PSCs, respectively, while also providing a potential route for tandem optoelectronics.