Shape‐Controlled Solution‐Epitaxial Perovskite Micro‐Crystal Lasers Rivaling Vapor Deposited Ones

Abstract

Epitaxial growth methods usually need dedicated equipment, high energy consumption to maintain pure vacuum conditions and evaporation of source materials, and elevated substrate temperatures. Solution epitaxial growth requires nothing of that but is rarely used because the achieved microstructures are of low quality, not homogeneous, and finally exhibit worse performances in devices. Here, an antisolvent‐vapor‐assisted‐crystallization of metal‐halide‐perovskites as a method overcoming these disadvantages is demonstrated. The methylammonium lead tribromide exhibits van‐der‐Waals type of epitaxial growth on mica substrates, resulting in micro‐crystallites whose shape can be controlled to be either triangular micro‐prism or micro‐cuboid. These micro‐crystallites act as optical resonators supporting various optical modes and lasing is achieved under optical excitation with low thresholds and record high environmental stability. Selecting suitable resonators from a large variety of sizes allows control of mode spacing and finally mono‐mode operation, considered to be an important feature of semiconductor laser devices. The achieved results are essentially competitive to those obtained by vapor phase epitaxial microstructures, highlighting that epitaxy of high‐quality optoelectronic device structures is feasible by minimum technological efforts and energy consumption, which are of increasing importance considering issues such as global warming and the current energy crisis.

Single Mode Lasing from CsPbBr3 Microcrystals Fabricated by Solid State Space‐Confined Growth

“…This lasing mode shift versus pump fluence is also mentioned in some literature. [ 53,55 ] The lasing emission stability up to 1.1 × 10 5 pulses in the ambient condition is displayed in Figure 6c, indicating the material and cavity are stable under ns laser excitation. It can be ruled out that the blueshift is caused by the degradation of CsPbBr 3 material.…”

“…F-P cavity mode peak follows the equation m𝜆 mode = 2n r L, where m is the mode number, 𝜆 mode is the emission wavelength, n r is the refractive index of the CsPbBr 3 , and L is the effective cavity length. [53] According to the mode condition 𝜆 mode /n r = constant, the decrease in refractive index will lead to a blueshift of laser mode.…”

“…Smooth sidewalls and end surfaces are shown in the atomic force microscope (AFM) imagined in Figure 4c. The refractive index steps at the perovskite/air and perovskite/glass interfaces will make waveguiding possible, [ 53 ] which is a prerequisite for laser devices. In Figure 4d, with increasing pump fluence, the PL spectrum change from relatively broad spontaneous emission to narrow lasing spikes at the lower energy shoulder with 2.73 nm FSR.…”

“…F–P cavity mode peak follows the equation mλ mode = 2 n r L , where m is the mode number, λ mode is the emission wavelength, n r is the refractive index of the CsPbBr 3 , and L is the effective cavity length. [ 53 ] According to the mode condition λ mode / n r = constant, the decrease in refractive index will lead to a blueshift of laser mode. Compared to the temperature effect in the 30 min stability test, the carrier density induced refractive index decrease is attributed to the main reason for the blueshift considering its fast reversible nature.…”

The Effect of Changing the Nano Size and Crystal Spacing on the Energy Gap and Other Optical and Electrical Properties of Ba_xFe_(1-x)TiO₄ Perovskite Cells and Their Theoretical Relations

“…In the paper published by Sonali Mehra et al [16] he studied the behavior of halide perovskites, this work mainly focuses on synthesizing and evaluating the efficiency of methyl ammonium lead halide-based perovskite (MAPbX3; X=Cl, Br, I) solar cells. The preparation technique is based on the colloidal Hot-injection method (HIM) to synthesize MAPbX3 (X=Cl, Br, I) perovskites using the specific precursors and organic solvents under ambient conditions.…”