Abstract
Interfacial modification (IM) plays a vital role in boosting the performance of perovskite solar cells. Herein, we demonstrate a new strategy in which zinc sulfide (ZnS) is used as an interfacial modifier between mesoporous-TiO2 (mp-TiO2) and a CH3NH3PbI3 absorber layer via the successive ionic layer adsorption and reaction method. The layer thickness of ZnS was optimized, and its effects on the conduction band position, interfacial charge recombination, and photovoltaic performance were investigated. Our results revealed that an ultrathin ZnS layer on mp-TiO2 helps in suppressing backflow of electrons, effectively reducing interfacial charge recombination and facilitating electron transfer. Our best performing perovskite solar cell device using the mp-TiO2-ZnS achieved a power conversion efficiency of 14.9%, with an open-circuit voltage of 1.02 V, short-circuit current density of 19.05 mA cm−2, and fill factor of 75.43%. Our simple ZnS IM approach proves that interface engineering could be a key strategy in improving the performance of perovskite solar cells.
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•Interfacial modification can improve the performance of perovskite solar cells.•Ultrathin ZnS as an interfacial modifier is deposited on the mesoporous TiO2 ETL.•The ZnS-modified TiO2 device shows a power conversion efficiency of 14.9%.•ZnS significantly reduces interfacial charge recombination and enhances charge extraction.