Approaching 24% Efficiency in Four-Terminal Perovskite/CZTSSe Tandem Solar Cells Using Diphenylammonium Chloride Additive-Based Wide-Bandgap Perovskite Absorber.

In the quest for high-efficiency photovoltaics, tandem solar cells combining perovskite and CZTSSe (copper zinc tin sulfide selenide) hold significant promise. This study explores the integration of diphenylammonium chloride (DPACl) as an additive within a wide-bandgap (WBG) perovskite layer to enhance the performance of a four-terminal (4-T) hybrid tandem solar cells (HTSCs) device. The DPACl additive has been systematically optimized and utilized for WBG perovskite solar cells (PSCs). Here, an optimum amount of DPACl additive effectively enhances the quality of perovskite films, and improves charge carrier dynamics thereby reducing non-radiative recombination losses. An optimized 2 mg mL-1 DPACl-based PSC achieved a power conversion efficiency (PCE) of 19.66% with thehighest open circuit voltage (VOC) of 1.172 V. Further, the WBG-based PSCs integrate into a 4-T mechanically stacked with narrow bandgap (NBG-1.05 eV)-based CZTSSe for HTSCs, which demonstrates a high PCE of 23.96%. This research contributes essential insights into the development of efficient photovoltaic systems based on perovskite and CZTSSe tandem architectures.