Abstract
Photonic devices based on perovskite materials are considered promising alternatives for a wide range of these devices in the future because of their broad bandgaps and ability to contribute to light amplification. The current study investigates the possibility of improving the light amplification characteristics of CsPbBr3 perovskite quantum dot (PQD) films using the surface encapsulation technique. To further amplify emission within a perovskite layer, CsPbBr3 PQD films were sandwiched between two transparent layers of poly(methyl methacrylate) (PMMA) to create a highly flexible PMMA/PQD/PMMA waveguide film configuration. The prepared perovskite film, primed with a polymer layer coating, shows a marked improvement in both emission efficiency and amplified spontaneous emission (ASE)/laser threshold compared with bare perovskite films on glass substrates. Additionally, significantly improved photoluminescence (PL) and long decay lifetime were observed. Consequently, under pulse pumping in a picosecond duration, ASE with a reduction in ASE threshold of ~1.2 and 1.4 times the optical pumping threshold was observed for PQDs of films whose upper face was encapsulated and embedded within a cavity comprising two PMMA reflectors, respectively. Moreover, the exposure stability under laser pumping was greatly improved after adding the polymer coating to the top face of the perovskite film. Finally, this process improved the emission and PL in addition to enhancements in exposure stability. These results were ascribed in part to the passivation of defects in the perovskite top surface, accounting for the higher PL intensity, the slower PL relaxation, and for about 14 % of the ASE threshold decrease.
Highlights
Powerful and intense photoluminescence (PL), low non-radiative recombination rates, and long carrier lifetimes in pure and mixed perovskites have expanded their application in optoelectronic devices, such as light-emitting diodes (LEDs), lasers, and photodetectors [1,2,3,4,5,6,7,8,9]
Evaluation of photoluminescence with optical pumping: As demonstrated in previously published work [23], the threshold properties and gain characteristics of poly(methyl methacrylate) (PMMA)/ perovskite can be controlled by changing the polymer thickness
The perovskite layer was coated to examine the optical response of the perovskite film after passivation of the surface by PMMA
Summary
Powerful and intense photoluminescence (PL), low non-radiative recombination rates, and long carrier lifetimes in pure and mixed perovskites have expanded their application in optoelectronic devices, such as light-emitting diodes (LEDs), lasers, and photodetectors [1,2,3,4,5,6,7,8,9]. Inorganic cations (e.g., CsPbX3) show relatively improved stability compared with those of organic–inorganic hybrid counterparts (e.g., MAPbX3 and FAPbX3), CsPbX3 PQDs in practical operation are still very sensitive to polar solvents and moisture, anion exchange reactions, and heating All of these are due to the low formation energy of the crystal lattice and the high decentralization activity of surface ions [2,3,4,5,6,7]. QDs, as well as other nanomaterials, have a large specific surface area, which greatly affects their intrinsic properties Their inherent instability impedes further development and future application of CsPbX3 PQDs in optoelectronics and in other fields. It is crucial to explore an effective pathway to enhance the stability of CsPbX3 perovskite QDs
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