Front-Contact Passivation of PIN MAPbI₃ Solar Cells with Superior Device Performances

Perovskite materials have attracted widespread attention in the photovoltaic community due to their excellent intrinsic electronic properties and very high device efficiency. Interfacial passivation for perovskite solar cells has been demonstrated as a valid approach for fabricating high-efficiency solar cells. However, in planar inverted (PIN) device configuration, the mechanistic understanding of how front-contact passivation (FCP) between perovskite and dopant-free organic hole-transporting materials enhances the device performance remains elusive. Considering the direct impact of FCP on the perovskite layer, we select poly(methyl methacrylate) (PMMA) as the FCP layer being inserted between dopant-free poly(triarylamine) (PTAA) and MAPbI3. Our results show that PMMA can promote the hydrophilicity of PTAA, improve the interfacial contact with MAPbI3, facilitate the charge carrier transfer, and reduce the interface-mediated recombination. This PMMA FCP dramatically boosted the device open-circuit voltage (Voc) from 1.04 V to 1.10 V. Furthermore, the performance of the champion device with negligible hysteresis is enhanced from 17.39 % to 19.51%, which is among the highest efficiencies via the unilateral passivation layer.