The Role of Bulk and Interface Recombination in High‐Efficiency Low‐Dimensional Perovskite Solar Cells

2D Ruddlesden-Popper perovskite (RPP) solar cells have excellent environmental stability. However, the power conversion efficiency (PCE) of RPP cells remains inferior to 3D perovskite-based cells. Herein, 2D (CH3 (CH2 )3 NH3 )2 (CH3 NH3 )n-1 Pbn I3n+1 perovskite cells with different numbers of [PbI6 ]4- sheets (n = 2-4) are analyzed. Photoluminescence quantum yield (PLQY) measurements show that nonradiative open-circuit voltage (VOC ) losses...