Excitonic Feature in Hybrid Perovskite CH3NH3PbBr3 Single Crystals

We have measured the temperature dependence of the reflection and photoluminescence spectra of a lead bromide hybrid material (CH3NH3PbBr3) using high-quality macroscopic single crystals. Single crystals provide clear and sample-independent reflection spectra that permit discussion of the properties of the photoexcited carriers. We have found that excitons still exist in CH3NH3PbBr3, even at room temperature. We have also determined the temperature dependence of the exciton resonance energy and the line width.