Reveal the large open-circuit voltage deficit of all-inorganicCsPbIBr2 perovskite solar cells

Due to excellent thermal stability and optoelectronic properties, all-inorganic perovskite is one of the promising candidates to solve the thermal decomposition problem of conventional organic—inorganic hybrid perovskite solar cells (PSCs), but the larger voltage loss (V_loss) cannot be ignored, especially CsPbIBr₂, which limits the improvement of efficiency. To reduce V_loss, one promising solution is the modification of the energy level alignment between the perovskite layer and adjacent charge transport layer (CTL), which can facilitate charge extraction and reduce carrier recombination rate at the perovskite/CTL interface. Therefore, the key issues of minimum V_loss and high efficiency of CsPbIBr₂-based PSCs were studied in terms of the perovskite layer thickness, the effects of band offset of the CTL/perovskite layer, the doping concentration of the CTL, and the electrode work function in this study based on device simulations. The open-circuit voltage (V_oc) is increased from 1.37 V to 1.52 V by replacing SnO₂ with ZnO as the electron transport layer (ETL) due to more matching conduction band with the CsPbIBr₂ layer.