Wafer-scale monolayer MoS film integration for stable, efficient perovskite solar cells.

One of the primary challenges in commercializing perovskite solar cells (PSCs) is achieving both high power conversion efficiency (PCE) and sufficient stability. We integrate wafer-scale continuous monolayer MoS buffers at the top and bottom of a perovskite layer through a transfer process. These films physically block ion migration of perovskite into carrier transport layers and chemically stabilize the formamidinium lead iodide phase through strong coordination interaction. Effective chemical passivation results from the formation of Pb-S bonds, and minority carriers are blocked through a type-I band alignment. Planar p-i-n PSCs (0.074 square centimeters) and modules (9.6 square centimeters) with MoS/perovskite/MoS configuration achieve PCEs up to 26.2% (certified steady-state PCE of 25.9%) and 22.8%, respectively. Moreover, the devices show excellent damp heat (85°C and 85% relative humidity) stability with <5% PCE loss after 1200 hours and notable high temperature (85°C) operational stability with <4% PCE loss after 1200 hours.