Regulation of the Buried Interface to Achieve Efficient HTL-Free All-Inorganic CsPbIBr-Based Perovskite Solar Cells.

The large voltage loss () mainly stems from the mismatch between the perovskite film and electron transport layer in CsPbIBr-based all-inorganic perovskite solar cells (I-PSCs), which restricts the power conversion efficiency (PCE) of devices. To address this issue, potassium benzoate (BAP) is first introduced as a bifunctional passivation material to regulate the TiO/CsPbIBr interface, reduce the , and improve the photovoltaic performance of CsPbIBr-based I-PSCs. Eventually, the champion PCE of CsPbIBr-based I-PSCs without a hole transport layer modified by BAP (Target-PSCs) improves to 14.