Temperature-Dependent Amplified Spontaneous Emission in CsPbBr3 Thin Films Deposited by Single-Step RF-Magnetron Sputtering

Abstract

Due to their high optical efficiency, low-cost fabrication and wide variety in composition and bandgap, halide perovskites are recognized nowadays as real contenders for the development of the next generation of optoelectronic devices, which, among others, often require high quality over large areas which is readily attainable by vacuum deposition. Here, we report the amplified spontaneous emission (ASE) properties of two CsPbBr3 films obtained by single-step RF-magnetron sputtering from a target containing precursors with variable compositions. Both the samples show ASE over a broad range of temperatures from 10 K up to 270 K. The ASE threshold results strongly temperature dependent, with the best performance occurring at about 50 K (down to 100 µJ/cm2), whereas at higher temperatures, there is evidence of thermally induced optical quenching. The observed temperature dependence is consistent with exciton detrapping up to about 50 K. At higher temperatures, progressive free exciton dissociation favors higher carrier mobility and increases trapping at defect states with consequent emission reduction and increased thresholds. The reported results open the way for effective large-area, high quality, organic solution-free deposited perovskite thin films for optoelectronic applications, with a remarkable capability to finely tune their physical properties.

Modal gain enhancement of perovskite nanosheets by a patterned waveguide via spectral-length gain analysis

“…Whilst PL is associated with the relaxation and transfer of excited carrier population, gain is governed by the density of states, whereby the population inversion density is determined. It was known that the PL spectrum of CsPbBr 3 nanostructures is dominated by the defect states of Br vacancies and surface states, and the energy levels located below and above the exciton state were estimated by the thermal activation energy [39][40][41][42]. Consequently, the gain of CsPbBr 3 nanostructures is expected to appear with a large spectrum width (∼ 20 meV).…”