Paradoxical Approach with a Hydrophilic Passivation Layer for Moisture-Stable, 23% Efficient Perovskite Solar Cells

Since the first report on the ∼10% efficient solid-state perovskite solar cell (PSC) in 2012, perovskite photovoltaics surged swiftly. Although there has been a quantum leap in the power conversion efficiency (PCE), stability has still been an issue despite considerable progress in material and device stability. In this report, we propose a paradoxical approach for improving the stability of perovskite against moisture, which is a surface treatment of perovskite film with hydrophilic 2-aminoethanol hydroiodide (2AEI) or 4-amino-1-butanol hydroiodide (4ABI). The post-treated hydrophilic materials protect effectively the underneath perovskite layer from moisture because water molecules are absorbed by the hydrophilic layer. Over 90% of the initial PCE is retained after 1000 h stored under relative humidity of ∼20%, while a faster degradation is monitored from the untreated perovskite layer. The surface anchored hydrophilic materials are found to improve PCE simultaneously, leading to a value of 23.25%, due to lowered trap-state distribution by passivating surface defects.