Additive engineering with sodium azide material for efficient carbon-based perovskite solar cells

Perovskite solar cells with carbon electrodes (C-PSCs) are one of the low-cost and new-generation solar cell technologies to solve global energy demands. In the current research, an additive engineering approach to a perovskite precursor based on sodium azide (NaN3) material was employed to fabricate stable and efficient C-PSCs. The NaN3 additive boosted perovskite solution spreading on the SnO2 electron transport layer (ETL), resulting in a well-oriented perovskite layer with improved micro-morphology. The NaN3 additive reduced non-radiative charge recombination through the reduction of the trap density within the perovskite layer. This increased the photovoltaic performance and generated C-PSCs with a champion efficiency of 14.90%, higher than the 12.94% obtained for the unmodified C-PSCs. Indeed, the NaN3 modifier increased the J(SC) and fill factor (FF) parameters by reducing charge transfer resistance (R-ct) and increasing charge recombination resistance (R-rec). In addition, it was observed that the NaN3-modified C-PSCs present higher shelf and ambient stability than the unmodified C-PSCs, revealing the potential of the NaN3 material for assembling efficient and stable C-PSCs.