Lead halide perovskites have received much attention as a novel photoactive material, and can be used in a variety of optoelectronic applications. Optoelectronic and electronic devices based on perovskite materials are relatively less complicated to produce and are ideal for mass production or integration into classical electronic devices.

In a study published in Advanced Optical Materials, the researchers at the Changchun Institute of Optics, Fine Mechanics and Physics of the Chinese Academy of Sciences and the collaborators made a breakthrough in the field of lead halide perovskite optoelectronic device. They have synthesized CsPbBr₃ microplates and fabricated high efficiency phototransistors using these high-crystallinity CsPbBr₃ microplates.

Through the space-limited and inverse temperature crystallization strategy, the researchers synthesized high quality CsPbBr₃ microplate with no obvious grain boundary. The thickness of the CsPbBr₃ microplate they produced is about 2 μm, and the size can reach millimeter or lager, which is convenient for use in electronic and optoelectronic devices.

Phototransistors made with these CsPbBr₃ microplates showed anomalous ambipolar transport characteristics at room temperature. The hole mobility showed light dependence, while the electron mobility was identical under various light incidence.

Besides, the threshold voltage in electron-transport model showed light dependence, however the phenomenon did not exist when hole is majority charge carriers. This is the first time this phenomenon has been reported in perovskite materials.

The researchers believe that the anomalous transport behavior can be attributed to photovoltaic and photoconductive effects. Moreover, the hole (electron) mobility reached 0.34 (0.40) cm² V^-1 s^-1 under light illumination with the power density of 50 mW cm^-2, which is the highest value ever reported for CsPbBr₃ perovskite by far.

This study is desirable for revealing the intrinsic transport property of CsPbBr₃ material, especially for devices working under light illumination conditions, such as photovoltaics, photoconductor and light emitting devices.