Electronic implications of organic nitrogen lone pairs in lead iodide perovskites
Hybrid halide perovskites composed of protic organic A-site cations are promising materials for the conversion of light into electricity. Polycrystalline technologies are of particular interest because of their desirable processability, but suffer from decreased efficiency compared to single crystal devices, in part owing to trap states at grain boundaries. Recent remedies for increasing performance of polycrystalline lead iodide-based perovskites include additional organic polymers at grain boundaries, serving to both prevent material decomposition and passivate the grain. Here we demonstrate that, using the 2D perovskite architecture as an analogue for the 3D material, passivating layers containing nitrogen lone pairs may act as chromophores, resulting in poor material performance.