Band-Edge Luminescence from Oxide and Halide Perovskite Semiconductors

Because perovskite crystals exhibit unique magnetic, conductive, and optical properties, they have been the subject of many fundamental investigations in various research fields. However, investigations related to their use as optoelectronic device materials are still in their early days. Regarding oxide perovskites, which have been investigated for a long time, the efficiency of photoluminescence (PL) induced by band-to-band transitions is extremely low because of the localized nature of the carriers in these materials. On the other hand, halide perovskites exhibit a highly efficient band-edge PL attributable to the recombination of delocalized photocarriers. Therefore, it is expected that this class of high-quality materials will be advantageous for optoelectronic devices such as solar cells and light-emitting diodes. In this Minireview, we discuss various aspects of the PL properties and carrier dynamics of SrTiO₃ and CH₃ NH₃ PbX₃ (X=I, Br), which are representative oxide and halide perovskites.