High-Quality CsPbBr_3 Perovskite Films with Modal Gain above 10 000 cm~(?1) at Room Temperature

摘要

Halide perovskite lasers based on CsPbBr_3 micro- and nanoscale crystalshave demonstrated fascinating performance owing to their low-thresholdlasing at room temperature and cost-effective fabrication. However, chemicallysynthesized thin films of CsPbBr_3 usually have rough polycrystallinemorphology along with a large amount of crystal lattice defects and, thus,are mostly utilized for the engineering of light-emitting devices. This obstacleprevents their usage in many photonic applications. Here, a protocol todeposit large-grain and smooth CsPbBr_3 thin films is developed. Their highquality and large scale allow to demonstrate a maximum optical gain up to12 900 cm~(?1) in the spectral range of 530–540 nm, which is a record-high valueamong all previously reported halide perovskites and bulk semiconductors(e.g., GaAs, GaN, etc.) at room temperature. Moreover, femtosecond laserablation technique is employed to create high-quality microdisc lasers onglass from these films to obtain excellent lasing characteristics. The revealedcritical roles of thickness and grain size for the CsPbBr_3 films with extremelyhigh optical gain pave the way for development of low-threshold lasers orultimately small nanolasers, as well as to apply them for polaritonic logicalelements and integrated photonic chips.