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<p>Triplet–triplet annihilation upconversion sensitized by quantum dot is often limited by the short exciton lifetime, necessitating tethered triplet transmitter. Here, we report a transmitter-free system of ZnSe quantum dot and 2,5-diphenyloxazole achieving 24% upconversion quantum yield, the highest for quantum dot sensitization upconversion. The upconversion quantum yield peaks at 30 mM 2,5-diphenyloxazole. Transient spectroscopy shows the triplet energy transfer efficiency is over 80% regardless of the 2,5-diphenyloxazole concentration, but the triplet–triplet annihilation efficiency dominates the overall upconversion quantum yield and shows a strong dependence on the 2,5-diphenyloxazole concentration that increases first from 10% to 25%, then decreases. The optimal concentration is achieved when the triplet 2,5-diphenyloxazole collision probability is highest, thus ensuring a maximum triplet–triplet annihilation efficiency. This work demonstrates a design principle of binary quantum dot upconversion system and reveals the critical role of modulating emitter concentration for optimal upconversion quantum yield.</p>

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High-yield visible-to-ultraviolet upconversion by ZnSe quantum dots with dynamic triplet transfer

  • 期刊论文

  • 出版模式：

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  • 发表日期：

    2026年7月17日

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  • Xin Zhang,
  • Rongxin Zhang,
  • Lei Wang,
  • Feng Chen,
  • Shan He,
  • Zihao Xu,
  • Zhigang Xia,
  • Guijie Liang

摘要

Triplet–triplet annihilation upconversion sensitized by quantum dot is often limited by the short exciton lifetime, necessitating tethered triplet transmitter. Here, we report a transmitter-free system of ZnSe quantum dot and 2,5-diphenyloxazole achieving 24% upconversion quantum yield, the highest for quantum dot sensitization upconversion. The upconversion quantum yield peaks at 30 mM 2,5-diphenyloxazole. Transient spectroscopy shows the triplet energy transfer efficiency is over 80% regardless of the 2,5-diphenyloxazole concentration, but the triplet–triplet annihilation efficiency dominates the overall upconversion quantum yield and shows a strong dependence on the 2,5-diphenyloxazole concentration that increases first from 10% to 25%, then decreases. The optimal concentration is achieved when the triplet 2,5-diphenyloxazole collision probability is highest, thus ensuring a maximum triplet–triplet annihilation efficiency. This work demonstrates a design principle of binary quantum dot upconversion system and reveals the critical role of modulating emitter concentration for optimal upconversion quantum yield.