Near-unity blue-orange dual-emitting Mn-doped perovskite nanocrystals with metal alloying for efficient white light-emitting diodes
2021
Ji, Sihang | Yuan, Xi | Zheng, Jinju | Cao, Sheng | Ji, Wenyu | Li, Haibo | Zhao, Jialong | Zhang, Hanzhuang
The tunable dual-color emitting Mn²⁺ doped CsPbCl₃₋ₓBrₓ nanocrystals (NCs) with near-unity photoluminescence quantum yield (PL QY) were synthesized through post-treatment of metal bromide at room temperature for fabrication of efficient warm white light-emitting diodes (WLEDs). Especially, the CdBr₂ treated blue-orange emitting Mn doped NCs with various Mn/Pb molar feed ratios exhibit higher PL QY of 97% and longer Mn²⁺ PL lifetime of 0.9 ms. It is surprisingly found that the X-ray diffraction peak at 31.9° is almost not changed with increasing Br composition, meaning formation of metal alloying due to incorporation of amount of divalent cation in NCs. The strong and stable Mn²⁺ PL at temperature ranging from 80 K to 360 K are revealed and the temperature-dependent energy transfer efficiencies in Mn²⁺ doped CsPbCl₁.₅Br₁.₅ NCs are obtained. The enhancement mechanism of Mn²⁺ PL QY was attributed to improved energy transfer from exciton to Mn²⁺ d–d transition and suppressed defect state density after post-treatment. The efficient warm WLEDs with color rendering index of 90 and luminous efficacy of 92 lm/W at 10 mA were fabricated by combining blue-orange dual-emitting Mn²⁺ doped CsPbCl₃₋ₓBrₓ@SiO₂ and green emissive CsPbBr₃@SiO₂ NCs with violet GaN chips.
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