High dielectric constant ethanolamine based two-dimensional perovskite thin films and their application in perovskite PSCs

In recent years, the extensive exploration of two-dimensional (2D) perovskites in the perovskite solar cell field has been driven by their remarkable humidity stability and tunable optoelectrical properties. However, the device performance in solar cells is hampered by the constraints posed by the quantum and dielectric confinement effects. In this study, ethanolamine (EA+) with a high dielectric constant was introduced as a spacer cation to fabricate 2D perovskite (EA)2(MA)4Pb5I16 films. The investigation focused on evaluating the influence of various additives on the crystallinity, surface morphology, light absorption capacity, and carrier lifetime of EA+-based perovskite thin films. By incorporating MACl as an additive, we achieved smooth and compact perovskite thin films of superior quality, leading to perovskite solar cells (PSCs) with a remarkable photovoltaic efficiency of 10.24%. Furthermore, the unencapsulated (EA)2(MA)4Pb5I16-based device maintained 83% of its original efficiency after 840 h of storage in ambient conditions, outperforming the 2D perovskite counterpart that employed phenethylamine (PEA+) as the spacer cation with a dielectric constant of 3.314. These results convincingly demonstrate that the strategic incorporation of high dielectric constant organic cations into 2D PSCs offers a promising avenue for elevating their efficiency and humidity stability.