Improving the Performance of a CH₃NH₃PbBr₃ Perovskite Microrod Laser through Hybridization with Few-Layered Graphene

Lead halide perovskite micro- and nanolasers have been thoroughly studied in past two years. Record low threshold and high Q factor have been demonstrated in perovskite nanorods. However, most of the researches are focusing on the observations of lasing actions. The performances of perovskite microlasers at high excitation power, which are supposed to be more important in applications such as displays and laser sources, have not been studied. Herein the perovskite microlasers have been studied at high pumping density and the mechanism to improve their performances has been explored. Different from the typical gain saturation, the perovskite microlaser shows a flat or a negative power slope at high pumping density and its total output power is thus limited. By transferring CH₃NH₃PbBr₃ perovskite microrod onto a few-layered graphene slice, it is found that the total output intensity has been significantly enhanced more than four times and the threshold is reduced around 20%. The following experiments show that the improvements are attributed to the electron acceptor property of graphene and the long carrier diffusion length. As the electrons are attracted by graphene, the electrons and holes are separated in different regions in the hybrid perovskite/graphene system and thus the Auger recombination at high pumping power can be dramatically reduced. The finding of this study will be important not only for the perovskite lasers but also for other semiconductor lasers.