Key Laboratory of Photochemical Conversion and Optoelectronic Materials, Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, Beijing 100190, China.
University of Chinese Academy of Sciences, Beijing 100049, China.
J Phys Chem Lett. 2021 Oct 7;12(39):9525-9530. doi: 10.1021/acs.jpclett.1c02717. Epub 2021 Sep 24.
Triplet-triplet annihilation (TTA) upconversion has shown promising potentials in the augmentation of solar energy conversion. However, challenging issues exist in improving TTA upconversion efficiencies in solid-states, one of which is the back energy transfer from upconverted singlet annihilators to sensitizers, resulting in decreasing upconversion emission. Here we present a light-harvesting molecular wire consisting of dendrons with 9,10-diphenylanthracene derivatives (DPAEH) at the periphery and -phenylene ethynylene oligomers (PPE) as the wire core. The peripheral DPAEH antenna funnels singlet excitonic energy to the wire on a 12 ps time scale. Incorporating the molecular wire into the TTA upconversion solid consisting of the DPAEH annihilator and the porphyrin sensitizer evidently improves the upconversion quantum yield from 1.5% to 2.7% upon 532 nm excitation by suppressing the back energy transfer from the singlet annihilator to the sensitizer. This finding offers a potential route to use a singlet energy light-harvesting architecture for enhancing TTA upconversion.
三重态-三重态湮灭（TTA）上转换在增强太阳能转换方面显示出了有前景的潜力。然而，在提高固态 TTA 上转换效率方面存在着挑战性的问题，其中之一是从上转换单重态湮灭剂到敏化剂的反向能量转移，导致上转换发射减少。在这里，我们提出了一种由树枝状分子组成的光收集分子线，其外围为 9,10-二苯基蒽衍生物（DPAEH），而线状核心为 -亚苯基乙炔低聚物（PPE）。外围的 DPAEH 天线在 12 ps 的时间尺度上将单重态激子能量传递到线状分子上。将分子线掺入由 DPAEH 湮灭剂和卟啉敏化剂组成的 TTA 上转换固体中，通过抑制从单重态湮灭剂到敏化剂的反向能量转移，在 532nm 激发下，上转换量子产率从 1.5%显著提高到 2.7%。这一发现为利用单重态能量光收集结构来增强 TTA 上转换提供了一种潜在途径。
