Efficient all-inorganic CsPbIBr2 perovskite solar cells with an open voltage over 1.33 V by dual-additive strategy

The internal non-radiative recombination and high trap-state density (Ntrap) in perovskite layer have severely limited the progress of low-temperature processed CsPbIBr2 perovskite solar cells (PSCs). In this work, cesium acetate (CsAc) and hydrogen lead triiodide (HPbI3) dual-additives are employed to tune the properties of CsPbIBr2 film prepared by low-temperature process. The CsAc material is used to modify CsPbIBr2 surface and optimize the CsPbIBr2/carbon electrode interface, while HPbI3 additive is employed to dope perovskite layer. The dual-additive strategy is used to optimize the microstructure and regulate the optoelectrical characteristics of carbon-based CsPbIBr2 PSCs. It is found that CsAc can passivate the vacancy defect of Br-, reduce the energy loss (Eloss) and enhance the open-circuit voltage (Voc)of PSCs. The HPbI3 additive works to optimize the crys-tallization process, resulting in the high-quality CsPbIBr2 films with better crystallinity and morphology. The modified films by CsAc and HPbI3 dual-additive demonstrate smaller band gap, better light absorption, reduced trap-state density (Ntrap) and suppressed carrier recombination. The optimized carbon-based PSCs modified by the dual-additive achieve a champion power conversion efficiency of 9.18% with a Voc of 1.334 V, more matched energy-level, reduced Eloss and promoted charge transfer. Moreover, the modified PSCs without encapsulation show improved long-term humid stability. Our work provides a facilitated method to prepare an efficient and stable CsPbIBr2 PSCs by low-temperature process.

Automated summary

In this work, CsAc and HPbI3 dual-additives are used to tune the properties of low-temperature processed CsPbIBr2 perovskite solar cells (PSCs). CsAc is used to modify the surface of CsPbIBr2 and optimize the interface, while HPbI3 is used to dope the perovskite layer. The dual-additive strategy can optimize the microstructure and regulate the optoelectrical characteristics of carbon-based CsPbIBr2 PSCs. The CsAc passivates the vacancy defect and improves the performance of PSCs, while the HPbI3 improves the crystallinity and morphology of CsPbIBr2 films and reduces trap-state density.