In triplet–triplet annihilation based photon upconversion, controlling triplet energy transfer (TET) through the system is key to unlocking higher efficiencies. In this work, we vary the size of colloidally synthesized CdSe nanocrystals (NCs) to examine the effects on TET during photon upconversion, using steady-state measurements and transient absorption spectroscopy. As the CdSe NC size increases, the photon upconversion quantum yield (QY) decreases due to the decrease in the rate of TET from CdSe to the surface bound anthracene transmitter ligand, as expected for the Marcus description of energy transfer from the transmitter to the NC. Long microsecond transmitter lifetimes are critical to high photon upconversion QYs.

中文翻译：

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蒽对CdSe纳米晶体光子上转换的尺寸依赖性。

在基于三重态-三重态an灭的光子上转换中，控制通过系统的三重态能量转移（TET）是释放更高效率的关键。在这项工作中，我们使用稳态测量和瞬态吸收光谱法，改变了胶体合成的CdSe纳米晶体（NCs）的尺寸，以研究光子上转换期间对TET的影响。随着CdSe NC尺寸的增加，由于从CdSe到表面结合的蒽递质的配体的TET速率降低，光子上转换量子产率（QY）降低，这是Marcus描述的从递质到NC的能量转移的预期。微秒级发射器的长寿命对于高光子上转换QY至关重要。