Photoluminescence Excitation Spectroscopy of Defect‐Related States in MAPbI 3 Perovskite Single Crystals

The MAPbI 3 halide perovskite single crystals are studied at 5 K temperature using the photoluminescence excitation spectroscopy. Two noninteracting types of states are determined: bound excitons and defect‐related states. Excitation of the crystal with light energy below the bound exciton resonance reveals the complex low‐density defect emission, otherwise hidden by the emission of bound excitons. A way to separate these defect‐related luminescence spectra is proposed, and the thorough study of this emission regime is carried out. The results of this study open an area of low‐density defect and dopant exploration in halide perovskite semiconductors.