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2 March 2020 Absorption and photoluminescence of ZnSe quantum dots synthesized by femtosecond laser ablation in microfluidics
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Abstract
Hyperbranched polyethylenimine coated zinc selenide (PEI-ZnSe) quantum dots were synthesized by femtosecond laser ablation in microfluidics. The PEI-ZnSe aqueous dispersions showed a strong green fluorescence at 500 nm. Based on Density functional theory, the defect energy level characteristics of different point defects in the Se-rich ZnSe quantum dots were studied. The results show that the shallow acceptor levels close to HOMO will be introduced into the bandgap by Se interstitial point defects, and the deep acceptor level close to LUMO will be introducted into the badgap by Se antisites point defect. According to the calculation results of defect energy levels, the energy level transition mechanism of quantum dot absorption and fluorescence emission were analyzed, and the types and quantities of defects existing in the quantum dots are discussed. The results show that the prepared PEI-ZnSe organic composite quantum dots have a large amount of SeZn and Sei defects, and the green fluorescence near 500 nm is the defect level luminescence (SeZn → Sei).
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Yuqin Zhang, Chao Yang, and Guoying Feng "Absorption and photoluminescence of ZnSe quantum dots synthesized by femtosecond laser ablation in microfluidics", Proc. SPIE 11268, Laser-based Micro- and Nanoprocessing XIV, 1126829 (2 March 2020); https://doi.org/10.1117/12.2565002
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