Simultaneous optimization of lead sequestration and electron transport layer via edible xylitol toward stable perovskite photovoltaics

As perovskite solar cell efficiencies approach theoretical limits, the design focus for next-generation charge transport materials has shifted from single-property optimization to multifunctional integration. This present study aims to synergistically address both non-radiative losses caused by bulk defects and environmental risks stemming from lead ion leakage. A non-toxic xylitol additive is proposed, and the chelating site of five hydroxyl groups endows xylitol with excellent depolymerization function and also inhibits lead leakage in perovskite layers. After xylitol optimization, the champion efficiency of PSCs fabricated on SnO₂ electron transport layers reach 21.7%. The PSC devices retain 92% of their initial PCE after 30 days in a nitrogen atmosphere. In contrast, SnO₂-based PSCs retain only 72% of their initial PCE. Furthermore, it is found that the lead-suppressed ETL on one side of the perovskite layer has a lead suppression capability of approximately 60%. More importantly, the functional integrity of the perovskite layer remains unaffected by the lead suppression effect of the ETL. Overall, the incorporation of xylitol significantly enhances the overall performance of PSC devices, thereby providing a promising way to address the advancement of high-efficiency, stable, and environmentally benign PSCs.