Two-Dimensional Perovskite Solar Cells with 14.1% Power Conversion Efficiency and 0.68% External Radiative Efficiency

Quasi-2D perovskites are attractive because of their improved stability compared to 3D counterparts, but they suffer from reduced performance. Here we report an efficient quasi-2D perovskite (PEA)2(MA)4Pb5I16-based optoelectronic device processed with NH4SCN and NH4Cl additives, showing a stabilized photovoltaic power conversion efficiency as high as 14.1% (average value 12.9 ± 0.8%), which is among the highest-performing quasi-2D perovskite solar cells. These additives increase the perovskite crystallinity and induce a preferred orientation with the (0k0) planes perpendicular to the substrate, resulting in improved transport properties and hence increased short-circuit current density. Furthermore, the NH4Cl treatment enriches the Cl– concentration near the PEDOT:PSS/perovskite interface, which passivates the electron traps, leading to an enhanced electroluminescence external quantum efficiency (0.68% at +2.5 V bias). As a result, high open-circuit voltages of 1.21 ± 0.01 V with a record low nonradiative VOC loss of only ∼0.16 V could be achieved for the quasi-2D perovskite system.