MacDonald Thomas S C, Tayebjee Murad J Y, Collins Miles I, Kumarasamy Elango, Sanders Samuel N, Sfeir Matthew Y, Campos Luis M, McCamey Dane R
ARC Centre of Excellence in Exciton Science, School of Physics, UNSW Sydney, Sydney, 2052, NSW, Australia.
School of Photovoltaic and Renewable Energy Engineering UNSW Sydney, Sydney, 2052, NSW, Australia.
J Am Chem Soc. 2023 Jul 19;145(28):15275-15283. doi: 10.1021/jacs.3c02672. Epub 2023 Jul 7.
The quintet triplet-pair state may be generated upon singlet fission and is a critical intermediate that dictates the fate of excitons, which can be exploited for photovoltaics, information technologies, and biomedical imaging. In this report, we demonstrate that continuous-wave and pulsed electron spin resonance techniques such as phase-inverted echo-amplitude detected nutation (PEANUT), which have emerged as the primary tool for identifying the spin pathways in singlet fission, probe fundamentally different triplet-pair species. We directly observe that the generation rate of high-spin triplet pairs is dependent on the molecular orientation with respect to the static magnetic field. Moreover, we demonstrate that this observation can prevent incorrect analysis of continuous-wave electron spin resonance (cw-ESR) measurements and provide insight into the design of materials to target specific pathways that optimize exciton properties for specific applications.
在单重态裂变过程中可能会产生五重态三重态对状态，它是决定激子命运的关键中间体，可用于光伏、信息技术和生物医学成像。在本报告中，我们证明了连续波和脉冲电子自旋共振技术，如相反转回波幅度检测章动（PEANUT），已成为识别单重态裂变中自旋路径的主要工具，可探测本质上不同的三重态对物种。我们直接观察到高自旋三重态对的产生速率取决于分子相对于静磁场的取向。此外，我们证明了这一观察结果可以防止对连续波电子自旋共振（cw-ESR）测量的错误分析，并为设计针对特定路径的材料提供见解，这些路径可优化激子特性以用于特定应用。
