Waterproof Cesium Lead Bromide Perovskite Lasers and Their Applications in Solution

Abstract

The many advantageous optoelectronic properties of lead halide perovskites have made them promising materials in both solar cells and light source applications. However, lead halide perovskites are soluble in polar solvents, which hinders their practical applications. Thus, the effective protection of perovskite against polar solvents is of great significance. Herein, we report a waterproof CsPbBr3 nanoplate (NP) laser protected by large-scale on-chip microprocess-compatible atomic layer deposition (ALD) Al2O3. The 50 nm Al2O3 coated CsPbBr3 NPs can continuously lase in water for over an hour and can still lase after being immersed in water for a month. Moreover, the lasing behaviors of the 20 nm Al2O3 coated CsPbBr3 NP, in the mixed solution of water and glycerine with the refractive index ranging from 1.33 to 1.47, are also studied. As the environmental refractive index increases, the NP laser goes through a mode selection process, showing single-mode (540.3 nm) to dual-mode and to single-mode (533.9 nm) lasing behavior, which is caused by mode competition resulting from the decrease of quality factor (Q factor) and the blue-shift of the material’s gain spectra. Besides, lasing thresholds of the CsPbBr3 NP increase with the environmental refractive index, which can be utilized for sensing with a measured sensitivity of 129.7 μJ cm–2 RIU–1 (per refractive index unit) (388.2 μJ cm–2 RIU–1) for the long (short)-wavelength lasing mode. Our work demonstrates that the ALD Al2O3 protection method can effectively protect CsPbBr3 against polar solvents, enhance the material’s stability, and enable perovskite’s practical applications in both on-chip integration and solvent systems.

Lead-free bright blue light-emitting cesium halide nanocrystals by zinc doping

“…Recently, cesium lead halide (CsPbX 3 , X ¼ Cl, Br, I) nanocrystals (NCs) have attracted extensive research interest in devices such as solar cells, 1-5 light-emitting diodes (LEDs), [6][7][8] and photodetectors [9][10][11] and in laser 12,13 applications due to their superior photonic and electronic properties. Among these NCs, the perovskite lattice structure is commonly taken and contributes to their excellent optoelectronic properties.…”

Perovskite nanowire lasers on low-refractive-index conductive substrate for high-Q and low-threshold operation

“…In particular, an increase in the lasing mode Q-factor enables hypersensitivity of the laser line to the environment changes such as the near-surface refractive index variation. It paves the way for the manufacturing of optical sensors analyzing the spectral response of a laser line in the presence of ultralow analyte concentrations in the surroundings [38]. Moreover, increasing the Q-factor of laser structures on a conductive substrate is extremely important for the development of electrically pumped deeply subwavelength nanolasers [16] and advanced high-Q microlasers [39], where the leakage of optical modes into the substrate might be almost eliminated.…”

Poly(catecholamine) Coated CsPbBr3 Perovskite Microlasers: Lasing in Water and Biofunctionalization

“…Appropriate encapsulation can protect LHP crystals from reactive molecules, enhancing device stability. However, methods to coat LHP, such as atomic layer deposition (ALD) [13,14] , calcination [15] , Van der Waals force [16] , and sol-gel processes [17][18][19] , have been limited to encapsulating ensembles of, not individual, LHP particles in macroscopic hydrophobic matrices. Furthermore, coating precursors used in these methods cause partial damages to LHPs [13,[15][16][17][18] , and the photoluminescence (PL) properties of LHP can be compromised [20] .…”

“…Appropriate encapsulation can protect LHP crystals from reactive molecules, enhancing device stability. Several post-synthetic methods have been demonstrated, such as atomic layer deposition (ALD) with amorphous alumina (AlO x ) [13] or aluminum oxide (Al 2 O 3 ), [14] calcination with titanium dioxide (TiO 2 ), [15] and sol-gel processes with silicon dioxides (SiO 2 ) [16,17] or hydrophobic polymer, [18][19][20][21] for embedding ensembles of LHP nanoparticles into a water-impermeable matrix. However, these methods have never been applied to encapsulate single individual particles.…”