Plenty of room on the top: pathways and spectroscopic signatures of singlet fission from upper singlet states

• Main Authors: Bai, Yiting, Ni, Wenjun, Sun, Kewei, Chen, Lipeng, Ma, Lin, Zhao, Yang, Gurzadyan, Gagik G., Gelin, Maxim F.
• Other Authors: School of Materials Science and Engineering
• Format: Article
• Language: English
• Published: 2023
• Subjects: Science::Chemistry::Physical chemistry; Coupling Reactions; Quantum Mechanics
• Online Access: https://hdl.handle.net/10356/165200
• Institution: Nanyang Technological University

We investigate dynamic signatures of the singlet fission (SF) process triggered by the excitation of a molecular system to an upper singlet state SN (N > 1) and develop a computational methodology for the simulation of nonlinear spectroscopic signals revealing the SN → TT1 SF in real time. We demonstrate that SF can proceed directly from the upper state SN, bypassing the lowest excited state, S1. We determine the main SN → TT1 reaction pathways and show by computer simulation and spectroscopic measurements that the SN-initiated SF can be faster and more efficient than the traditionally studied S1 → TT1 SF. We claim that the SN → TT1 SF offers novel promising opportunities for engineering SF systems and enhancing SF yields.