Correlation of Morphology and Interface Properties with Charge Transport in Wide Band Gap Perovskite Solar Cells

Wide band gap (WBG, E g ∼ 1.8 eV) perovskite solar cells (PSCs) are a key element for all-perovskite tandem solar cell technology. Here, we investigate the effect of morphology on the charge transport properties in PSCs with ∼1.8 eV absorbers. Morphologies are tuned via antisolvent dripping timings. Early dripping produces flat films with cracks, while delayed dripping results in a wrinkled morphology. Temperature-dependent photoluminescence measurements reveal that wrinkled films exhibit a lower activation energy, indicating improved charge transport. Further, scanning photocurrent microscopy reveals that wrinkled films possess significantly higher lateral charge transport lengths ( L ) for photoinduced charge carriers as compared to flat films, and a further improvement in L is achieved through interface passivation. This morphology-driven enhancement, along with interfacial engineering, reduces nonradiative voltage losses, yielding a power conversion efficiency of 18.54%. Thus this study establishes a direct correlation between morphology-induced enhancements in charge transport and minimized voltage losses in WBG PSCs.