Inverted Wide-Bandgap 2D/3D Perovskite Solar Cells with >22% Efficiency and Low Voltage Loss

Wide-bandgap perovskites play a key role in high-performance tandem solar cells, which have the potential to break the Schockley-Queisser limit. Here, a 2D/3D hybrid wide-bandgap perovskite was developed using octane-1,8-diaminium (ODA) as spacer. The incorporation of the ODA spacer can not only significantly reduce charge carrier nonradiative recombination loss but also inhibit phase separation. Moreover, with a synergy effect using butylammonium iodide (BAI) as a surface defect passivator, both the phase stability and device performance were further improved. Compared to the control inverted device with a V_OC of 1.16 V and a PCE of 18.50%, the optimized PSCs based on a surface processed 2D/3D perovskite exhibit a superior high V_OC of 1.26 V and a champion PCE of 22.19%, which is a record efficiency for wide-bandgap PSCs (E_g > 1.65 eV). This work provides a very effective strategy to suppress phase separation in wide-bandgap perovskites for highly efficient and stable solar cells.