Two-dimensional perovskite solar cells with high luminescence and ultra-low open-circuit voltage deficit

Abstract

High luminescence efficiency of the halide perovskite absorber layer in perovskite solar cells (PVSCs) will reduce the open-circuit voltage (V_oc) loss and further increase the cell efficiency. Still, while quasi-2D-structure perovskite films exhibit high emissivity in light-emitting devices, quasi-2D PVSCs show severe V_oc loss associated with non-radiative recombination. Here we demonstrate how the use of highly luminescent PEA_0.2BA_1.8MA₃Pb₄I₁₃ in quasi-2D PVSCs allows, via Cl⁻ passivation and heat-light post-co-treatment, a champion external electroluminescence quantum efficiency around 2.3% and a record low V_oc deficit of 0.36 eV. To our knowledge, this is the lowest V_oc loss for quasi-2D PVSCs and among the lowest for any type of PVSCs. As a result, high performance quasi-2D PVSCs are obtained, with a V_oc up to 1.29 V and 15.81% efficiency, showing excellent stability, and retain 98% of the original efficiency after heating at 85 °C for 1590 h. This work paves the way toward highly luminescent and efficient quasi-2D PVSCs.