Department of Chemistry, University of Copenhagen, Universitetsparken 5, DK-2100 Copenhagen Ø, Denmark.
Phys Chem Chem Phys. 2018 May 7;20(17):12182-12192. doi: 10.1039/c8cp00588e. Epub 2018 Apr 23.
Photon upconversion facilitated by triplet-triplet annihilation in molecular systems is a promising path toward utilization of sub bandgap photons in photovoltaic devices. Prior to the challenging synthesis of new molecules, quantum chemical computations can aid the design process and provide suggestions for new and optimal systems. Here, we benchmark time-dependent density functional methods by their ability to describe relevant photophysical quantities of a range of different types of sensitizer/annihilator pairs to provide guidelines for future computational studies of potential new pairs. Using meta-GGA, hybrid, and range-separated hybrid functionals, we find that the hybrid functionals B3LYP and PBE0 (incorporating low to medium fractions of exact exchange of 20% and 25%, respectively) describe singlet absorptions the best, while triplet energetics are best described by the meta-GGA functionals M06-L and M11-L (incorporating no exact exchange), respectively. Furthermore, we find that the Tamm-Dancoff approximation of time-dependent density functional theory in general does not improve the description of neither singlet nor triplet energies of sensitizer/annihilator pairs.
分子体系中的三重态-三重态湮灭促进的光子上转换是利用光伏器件中亚带隙光子的一种很有前途的途径。在具有挑战性的新分子合成之前，量子化学计算可以辅助设计过程并为新的和最优的体系提供建议。在这里，我们通过它们描述一系列不同类型敏化剂/湮灭剂对的相关光物理量的能力来对时间相关密度泛函方法进行基准测试，为未来对潜在新对的计算研究提供指导。使用泛函、杂化泛函和范围分离杂化泛函，我们发现杂化泛函 B3LYP 和 PBE0（分别包含 20%和 25%的低到中等分数的精确交换）对单重态吸收的描述最好，而三重态能最好由泛函 M06-L 和 M11-L（不包含任何精确交换）描述。此外，我们发现时间相关密度泛函理论的 Tamm-Dancoff 近似通常不能改善敏化剂/湮灭剂对的单重态和三重态能量的描述。
