High‐Quality CsPbBr₃ Perovskite Films with Modal Gain above 10 000 cm⁻¹ at Room Temperature

Abstract

nanolasers generating laser emission in the range of 420-824 nm, [1][2][3][4] , which can be simply synthesized from solution. First of all, such perovskites possess relatively high refractive index (larger than 2), which allows for the creation of self-resonating gain media placed on various substrates: dielectrics, [1][2][3][4] metals, [5] nanostructured, [6] photonic crystals, [7] as well as integrated with waveguiding systems. [8][9][10] Also, chemically synthesized CsPbX 3 perovskite single crystals [11] of high quality and different shapes (cuboids, [12,13] wires, [1,14,15] plates [16][17][18] ) exhibit high levels of optical gain (typically ≈10 3 cm −1 ) [19] larger than those of thin polycrystalline films synthesized from solution (typically ≈10 2 cm −1 ). Thus, they provide a powerful technological tool for micro-and nanolasers fabrication, when their precise positioning is not required. However, the fabrication of large-scale films with crystalline quality as high as for single crystals would allow for overcoming many technological obstacles hindering lithographical creation [9,20,21] of highly controllable designs for lasing applications.In this paper, we develop a high-temperature recrystallization method for chemical synthesis of large-grain CsPbBr 3 thin Halide perovskite lasers based on CsPbBr 3 micro-and nanoscale crystals have demonstrated fascinating performance owing to their low-threshold lasing at room temperature and cost-effective fabrication. However, chemically synthesized thin films of CsPbBr 3 usually have rough polycrystalline morphology along with a large amount of crystal lattice defects and, thus, are mostly utilized for the engineering of light-emitting devices. This obstacle prevents their usage in many photonic applications. Here, a protocol to deposit large-grain and smooth CsPbBr 3 thin films is developed. Their high quality and large scale allow to demonstrate a maximum optical gain up to 12 900 cm −1 in the spectral range of 530-540 nm, which is a record-high value among all previously reported halide perovskites and bulk semiconductors (e.g., GaAs, GaN, etc.) at room temperature. Moreover, femtosecond laser ablation technique is employed to create high-quality microdisc lasers on glass from these films to obtain excellent lasing characteristics. The revealed critical roles of thickness and grain size for the CsPbBr 3 films with extremely high optical gain pave the way for development of low-threshold lasers or ultimately small nanolasers, as well as to apply them for polaritonic logical elements and integrated photonic chips.

Room‐Temperature Exceptional‐Point‐Driven Polariton Lasing from Perovskite Metasurface

“…Our results explain the fundamental origin of the lasing in leadbromide metasurfaces and open new ways for the realization of room-temperature planar polariton lasers based on a rich variety of halide perovskites. Since the proposed cavity design is close to the most optimal case, we envision further lasing thresholds lowering through the material properties optimization via the synthesis of highly crystalline perovskite films [58][59][60] and cation engineering, [61] which can lead to low-cost continuous wave [62,63] and electrically pumped lasers, [64] essential for industrial applications.…”

Giant Ultrafast All-Optical Modulation Based on Exceptional Points in Exciton–Polariton Perovskite Metasurfaces

“…Note that the observed modulation time is constrained by the pulse widths of the utilized pump and probe and can potentially be reduced in systems with shorter pulses. Furthermore, in perovskite systems based on single crystals, characterized by lower nonradiative losses and lasing pump thresholds, 65 the pump power can be further minimized. In this context, the innovative concept of transmission modulation reliant on the polariton condensates in planar perovskite systems, as demonstrated in this study, holds immense promise as a cost-effective and versatile platform for developing robust ultrafast optical modulators for a wide range of applications.…”

Growth methods' effect on the physical characteristics of CsPbBr3 single crystal

“…19,20 The current literature predominantly focuses on quantum dots, nanocrystals, and thin films, underscoring the need for wellsuited CsPbBr 3 SCs for photodetector applications. [21][22][23] The cultivation of large SCs remains a technological challenge, crucial for industries utilizing SC ingots for advanced devices. 24 Achieving high-quality CsPbBr 3 SCs is essential in all contexts.…”