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

Wide band gap (WBG, Eg ∼ 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.