Low Threshold Two-Photon-Pumped Amplified Spontaneous Emission in CH₃NH₃PbBr₃ Microdisks

Abstract

Two-photon-pumped amplified spontaneous emission (ASE) of CH3NH3PbBr3 microdisks (MDs) were investigated by using femtosecond laser system. Low threshold at 2.2 mJ cm(-2) was obtained. Also, emission spectral tunability from 500 to 570 nm was demonstrated by synthesis the mixed halide perovskite MDs. The spatial effect of photoluminescence (PL) properties under one-photon and two-photon excitation were also studied by means of two-photon laser scanning microscope (TPLSM) and time-resolved PL spectroscopy. It was found that the band to band emission of near-surface regions and photocarriers' diffusion from near-surface regions to interior regions is significant for one-photon excitation. By contrast, reabsorption of emission under two-photon excitation plays a major role in the emission properties of the MDs. These results will give a more comprehensive understanding of the nonlinear effect of CH3NH3PbBr3 single crystals.

Single Crystal Perovskite Microplate for High‐Order Multiphoton Excitation

“…Right insets in Figure e,f illustrate the luminescence intensity and FWHM plots as a function of pump fluences, giving rise to a linear relationship with cubic pump fluence and a low STE threshold of E th ≈ 200 mJ cm −2 for MAPbBr 3 and E th ≈ 159 mJ cm −2 for CsPbBr 3 , suggesting that the three‐photon‐pump (3PP) STE has occurred in the MAPbBr 3 and CsPbBr 3 single microplate. To the best of our knowledge, there are only two reports on the multiphoton‐pumped amplified spontaneous emission (ASE) phenomenon of perovskite microplatelet single crystals, and they are only reported for the MAPbBr 3 system under up to two‐photon pumping . From the data comparison (as shown in Figure S7, Supporting Information), the threshold of the MAPbBr 3 in our work is slightly higher than the reported values, but the FWHM is narrower than the reported values, and the three‐photon‐pumped ASE is further reported in our work, which is more comprehensive in performance.…”

“…This causes the emission peak of the original Gaussian distribution to have a redshift of the emission peak and a partial cut of the left side, so that the emission line width is narrowed to some extent. According to the literature, in addition to the effects of reabsorption, the large emission redshift phenomenon should be attributed to the difference in band‐gap energy between the edge region and the interior region of the perovskite microplatelet single crystal. With the large redshift of the excitation wavelength (from 480 to 2100 nm), the greater the penetration depth of the incident photon, the main excitation region of the microplatelet crystal changes from the near surface edge to the inside of the crystal, resulting in a large emission redshift phenomenon.…”

“…Left insets in Figure a,b show micrographs of MAPbBr 3 and CsPbBr 3 single microplate under the femtosecond laser excitation at 480 nm beyond (upper inset) or below (lower inset) the STE threshold E th . The microplate emits strong greenish light from the four edges but much weaker emission from the interior regions, which is mainly due to the short penetration length upon single‐photon excitation that can only create photocarriers in the near‐surface regions while just small amount of photocarriers may diffuse to the interior regions …”

Edge Effect on the Population of Free Carriers and Excitons in Single‐Crystal CH3NH3PbBr3 Perovskite Nanomaterials

“…The free carriers dominated on the edges while the excitons in the interior regions. Despite transitions, the maximum normalized PL spectra (left inset) in the interior (magenta, e, 560 nm) shows unsymmetrical shape due to the strong self‐absorption effects, while that on the edges (black, a, 535 nm) shows the formal Gaussian profile …”

Enhancing Optically Pumped Organic-Inorganic Hybrid Perovskite Amplified Spontaneous Emission via Compound Surface Plasmon Resonance

“…The XRD pattern shown in Figure 2a showed MAPbBr3 crystal film diffraction peaks at 14.90° (100), 21.08° (110), 29.98° (200), 33.62° (210), 36.92° (211), 42.94° (220) and 45.68° (300). The XRD data indicated pure perovskite phase, which suggested a lamellar structure PbBr2 2D-layer parallel to the substrate [39]. In Figure 2a, the inset images display the MAPbBr3 film photographs (spin-coated on quartz/PEDOT: PSS) before and after ~365 nm UV lamp irradiation, respectively, and show a smooth surfaces.…”