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Ammonium acetate passivated CsPbI3 perovskite nanocrystals for efficient red light-emitting diodes
摘要： Lead halide perovskite nanocrystals (PNCs) have very recently emerged as promising emitters for their superior optoelectronic properties. However, the defects in perovskite itself make it susceptible to the external environment and internal ion migration, resulting in low photoluminescence quantum yield (PLQY) and poor device efficiency. Herein, we developed a method to reduce the surface defects of PNCs by introducing ammonium acetate in the synthesis of CsPbI3 PNCs. The addition of ammonium acetate can effectively eliminate undesired surface metallic lead cations and dangling bonds, resulting in an enhanced PLQY and stability. The passivated PNCs have an overall up-shift energy level, demonstrating better hole injection efficiency. As a result, the red light-emitting diodes (LEDs) fabricated with the passivated CsPbI3 PNCs achieved an optimal EQE of 10.6% and a maximum brightness of 981 cd/m2, which are 3.1 and 2.4 times that of unpassivated PNCs based devices, respectively.
关键词： CsPbI3 nanocrystals,ammonium acetate,defect passivation,photoluminescence quantum yield,light-emitting diodes
更新于2025-09-23 15:19:57
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Manipulation of Phase-Transfer Ligand-Exchange Dynamics of PbS Quantum Dots for Efficient Infrared Photovoltaics
摘要： Chemical surface treatment of colloidal quantum dots (CQDs) by phase-transfer ligand exchange (PTLE) is essential to implement highly densified, well-passivated CQD films for optoelectronic applications, such as infrared photovoltaics, light-emitting diodes and photodetectors. The PTLE, however, involves parallel and interactional processes of ligand exchange, phase transfer, and surface passivation of CQDs, which renders the optimization of PTLE still challenging. Herein, we explored the action mechanism of a widely-used additive, ammonium acetate (AA), on the PTLE of PbS CQDs in order to recognize the dynamic balance during the PTLE process and its impact on the performance of colloidal quantum dot solar cells (CQDSCs). Our research definitely shows that AA additive can modify the dynamics of PTLE by participating in all the three processes, and the amount of AA significantly influences the defect passivation and colloidal stability of PbS CQDs. At an appropriate concentration (~50 mM) of AA, PbS CQDs are well iodide-passivated by the PTLE, and the fabricated CQDSCs achieve the PCE of ~10% associated with the improved carrier transport and the reduced trap-assisted carrier recombination. However, excessive AA causes the trace residual AA on the CQD surface, resulting in the insufficient surface passivation of PbS CQDs and trap issues of CQDSCs. The double-edged sword effect of AA additive on the PTLE, demonstrated in our work, suggests that realizing the dynamic balance of different processes during PTLE is crucial for the further performance promotion of CQDSCs.
关键词： infrared photovoltaics,ammonium acetate,phase-transfer ligand exchange,colloidal quantum dots,surface passivation
更新于2025-09-11 14:15:04