Large-Scale Thin CsPbBr₃ Single-Crystal Film Grown on Sapphire via Chemical Vapor Deposition: Toward Laser Array Application

Abstract

Single-crystal perovskites with excellent photophysical properties are considered to be ideal materials for optoelectronic devices, such as lasers, light-emitting diodes and photodetectors. However, the growth of large-scale perovskite single-crystal films (SCFs) with high optical gain by vapor-phase epitaxy remains challenging. Herein, we demonstrated a facile method to fabricate large-scale thin CsPbBr3 SCFs (∼300 nm) on the c-plane sapphire substrate. High temperature is found to be the key parameter to control low reactant concentration and sufficient surface diffusion length for the growth of continuous CsPbBr3 SCFs. Through the comprehensive study of the carrier dynamics, we clarify that the trapped-related exciton recombination has the main effect under low carrier density, while the recombination of excitons and free carriers coexist until free carriers plays the dominate role with increasing carrier density. Furthermore, an extremely low-threshold (∼8 μJ cm–2) amplified spontaneous emission was achieved at room temperature due to the high optical gain up to 1255 cm–1 at a pump power of 20 times threshold (∼20 P th). A microdisk array was prepared using a focused ion beam etching method, and a single-mode laser was achieved on a 3 μm diameter disk with the threshold of 1.6 μJ cm–2. Our experimental results not only present a versatile method to fabricate large-scale SCFs of CsPbBr3 but also supply an arena to boost the optoelectronic applications of CsPbBr3 with high performance.

2D Metal‐Organic Complex Luminescent Crystals

“…The two distinct features reveal that the PL emission was dominated by the trap-assisted exciton recombination at lower excitation power (<1.2 mW), while bimolecular radiation recombination (free carrier recombination) of excitons is predominate at a higher power. [44,45] Such excitonic traps could be structural inhomogeneity, [46] surface defects, [47] oxygen, [48] etc. Besides, this recombination dynamic is also affected by temperature changes, which can be proved by power-dependent PL at low temperature.…”

Fabrication Methods for Integrating 2D Materials

“…On the other hand, for some of the newly developed materials such as MXenes and perovskites, the sample size is limited to several micrometers even with state-of-the-art synthesis methods, mainly because of their complicated material phase diagrams. [332] Synthesizing 2D films on wafer scales, especially in single crystal monolayer form, is important for the large-scale fabrication of integrated devices, for which MAME, MBE, and CVD have attracted significant attention. Fabrication efficiency is particularly important for industrial scale applications, and in this respect the low deposition speed of MBE represents a significant limitation, as does the manual manipulation nature of current MAME techniques.…”

Solvent Recrystallization‐Enabled Green Amplified Spontaneous Emissions with an Ultra‐Low Threshold from Pinhole‐Free Perovskite Films

“…G attains a value of ≈1100 cm −1 for P > 40 μJ cm −2 , which is comparable to that of CsPbBr 3 singlecrystalline thin films and nanocrystal films (Table 1). [36,40] However, the value of G for w/o-SR films was higher than that of films after SR with a maximum value of 2200 cm -1 at a comparable excitation density (Figures S6 and S7, Supporting Information). Thus, the reduced ASE threshold is attributed to the suppressed optical loss.…”