Bodipy与富勒烯桥联二聚体光敏剂参与的三重态-三重态湮灭荧光上转换过程的溶剂效应

Triplet-triplet annihilation (TTA) upconversion is one of the most advantaged photochemical techniques, and has been applied extensively on solar cells, photo-catalysis, photodynamic therapy and phosphorescent bioimaging. However, the solvent effect involved in the complicated TTA process has been neglected. We know, the viscosity can affect the quantum yield of triplet-triplet energy transfer, and moreover, the stabilization energies by solvent of photosensitizer and energy acceptor can also be changed by the solvent polarity, thus, the energy transfer channels via charge-separated state of photosensitizer are changed. In this project, some new Bodipy-fullerene dyads will be synthesized and applied in TTA upconversion of perylene in different solvents. Through measuring the femtosecond and nanosecond time-resolved transient absorption spectra and fluorescence emission spectra, the lifetime of triplet states, energy transfer rates and upconversion quantum yields can be obtained. With the aid of theoretical calculations, the solvent effect on decay dynamics of excited photosensitizer will be investigated, and the energy transfer and reaction mechanisms will be clarified. A general law of solvent effect on the photon upconversion system will be proposed.

三重态-三重态湮灭荧光上转换是实现可见光应用的先进手段之一，近年来在太阳能电池、光催化、光动力治疗和荧光成像等方面展现出明显的优势，然而其中涉及的溶剂效应一直是人们忽视的重要内容。众所周知，溶剂的粘度不仅影响三重态碰撞能量转移的效率，而且极性还将通过改变光敏剂和受体分子的溶剂稳定化能直接影响光敏剂电荷分离态的传能通道。为此，本项目中我们拟合成多种Bodipy与富勒烯桥联二聚体光敏剂，通过测量不同溶剂中的飞秒时间分辨和纳秒时间分辨的瞬态吸收光谱，获得其激发态寿命、传能速率和上转换量子产率，结合理论计算，系统研究溶剂极性和粘度等环境特征对此类光敏剂激发态分子衰变过程的影响，明确传能和反应机理，探讨此类荧光上转换体系溶剂效应的一般性规律。

近年来，三重态-三重态湮灭（TTA）上转换在太阳能电池、光催化、光动力治疗和荧光成像等方面展现出明显的优势，能够极大地促进相关过程效率的提高。然而，其中涉及的溶剂效应一直是人们忽视的重要内容。我们知道，溶剂效应不仅影响三重态能量转移效率，而且还能够有效改变光敏剂和受体分子的溶剂稳定化能，从而对荧光上转换过程的量子产率产生重要影响。为此，我们通过设计合成了多种Bodipy与富勒烯复合物为代表的光敏剂，与perylene或DPA等构成全新的TTA荧光上转换体系，在不同溶剂中开展其瞬态、稳态吸收光谱和荧光光谱测量，以及相应的动力学和寿命研究，获取了相应的荧光寿命、传能速率和上转换效率等参数。结合高精度的量子化学理论计算，系统地研究此类光敏剂分子性质，讨论其量子产率与化合物分子能级间隙的关系，建立溶剂粘度和极性等环境特征对相关的激发态分子衰变过程的影响，从而增强对相关光化学和光物理过程规律的认识，为发展更高上转换效率的光能材料提供理论线索。