Abstract
Perovskite quantum dots (PQDs) have emerged as promising competitive materials for optoelectronics and future energy applications. In this work, high-quality PQD thin films fabricated directly from the powdered form of CsPb(Br1-xClx)(3) compositions were investigated. Tunable light emission was achieved via (in general) composition modulation through a mixed halide (chloride/bromide) with different ratios of Cl-ion substitution of Br ions. The structural properties of the various compositions (alloys) as a function of the Cl content were investigated. These properties were correlated with the emitting colors and amplified spontaneous emission (ASE)/lasing performance, and the potential application of these properties in lighting devices and other optoelectronics devices was verified. These alloys consisted of a highly stable cubic phase that remained stable even at room temperature because of direct synthesis at a high temperature for all compositions. The Cl content had only a slight effect on the QD size. Moreover, the bandgaps of the alloys exhibited a strong dependence on the composition and increased rapidly with changing Br-to-Cl ratio through the halide ion exchange process. Furthermore, compositionally, the perovskite alloy was a photostable material and exhibited excellent photoluminescence quantum yields (PLQYs) and considerable photoluminescence. Alloys with a high Cl content underwent significant nonradiative decay, and the PLQYs decreased with increasing bandgap. These features were all dependent on ligand exchange from Br to Cl. In addition, ASE properties of these composition films were achieved and compared under long-term ambient conditions. Moreover, a low ASE threshold (21, 45, and 53 mu J/cm(2) for x = 0, 0.25, and 0.40, respectively) was obtained under picosecond laser excitation.