Dual Field Passivation Strategy for High-Performance Wide-Bandgap Perovskite Solar Cells

Wide-bandgap perovskite solar cells (WBG PSCs) have been receiving increasing focus due to the ideal application in tandem photovoltaics. Nonetheless, WBG perovskites tend to form high-density trap states, causing serious nonradiative recombination and phase segregation, which is detrimental to the efficiency and stability of WBG PSCs. In this work, a dual-field passivation strategy facilitated by isopropylamine hydroiodide (i-PAI) is introduced, in effect, showing both the molecular dipole field passivation and interface electric field passivation. This strategy reduces the charge trap density of WBG perovskite and suppresses the phase segregation, which is supported by the analysis of the experimental data and simulation results. Moreover, the dual functional passivation mitigates the open-circuit-voltage (VOC) deficit of the WBG (1.65 eV) PSCs to 0.39 V and increases the efficiency to a competitive value of 22.21%. The device also exhibits excellent photostability, maintaining 84.2% of the initial efficiency after 1080 h of illumination under 1-sun white LED. This work showcases a pivotal pathway to defect passivation that can markedly enhancing both the efficiency and stability of wide-bandgap perovskite solar cells.