Journal
NANOSCALE
Volume 14, Issue 3, Pages 919-929Publisher
ROYAL SOC CHEMISTRY
DOI: 10.1039/d1nr06549a
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Funding
- National Natural Science Foundation of China [U2001219, 51973064, 61935017]
- Natural Science Foundation of Guangdong Province [2019B030301003, 2019A1515012186]
- Guangdong Basic and Applied Basic Research Foundation [2019A1515012142]
- Guangzhou Science and Technology Plan Project [201904010384]
- State Key Lab of Luminescent Materials and Devices, South China University of Technology [Skllmd-2021-03]
- Macau Science and Technology Development Fund [FDCT-0044/2020/A1, FDCT-014/2017/AMJ]
- University of Macau [MYRG2018-00148-IAPME]
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Quasi-2D metal halide perovskites show reduced nonradiative losses by adjusting low-dimensional phase components and trap state density, leading to high photoluminescence quantum yield and improved crystal orientation, enabling high-performance green LEDs and low-threshold ASE.
Quasi-2D metal halide perovskites are promising candidates for light-emitting applications owing to their large exciton binding energy and strong quantum confinement effect. Usually, quasi-2D perovskites are composed of multiple phases with various numbers of layers (n) of metal halide octahedron sheets, enabling light emission from the lowest-bandgap phase by cascade energy transfer. However, the energy transfer processes are extremely sensitive to the phase distribution and trap density in the quasi-2D perovskite films, and the insufficient energy transfer between different-n phases and the defect-induced traps would result in nonradiative losses. Here, significantly reduced nonradiative losses in the quasi-2D perovskite films are achieved by tailoring the low-dimensional phase components and lowering the density of trap states. Butylammonium bromide (BABr) and potassium thiocyanate (KSCN) are employed to synergistically decrease the nonradiative recombination in the quasi-2D perovskite films of PEABr : CsPbBr3. The incorporation of BABr is found to suppress the formation of the n = 1 phase, while adding KSCN can further reduce the low-n phases, passivate the notorious defects and improve the alignment of the high-n phases. By incorporating appropriate contents of BABr and KSCN, the resultant quasi-2D perovskite films show high photoluminescence quantum yield (PLQY) and highly ordered crystal orientation, which enable not only the green light-emitting diodes (LEDs) with a high external quantum efficiency (EQE) of 16.3%, but also the amplified spontaneous emission (ASE) with a low threshold of 2.6 mu J cm(-2). These findings provide a simple and effective strategy to develop high-quality quasi-2D perovskites for LED and laser applications.
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