Singlet fission dynamics in high quality rubrene single crystals
Dmitry Maslennikov a, Marios Maimaris a, Navendu Mondal a, Haoqing Ning a, Shawn Zheng a, Yifan Dong a, Vitaly Podzorov b, Vladimir Bruevich b, Artem Bakulin a
a Imperial College London, Chemistry Department, UK
b Rutgers University, Physics Departments, USA
International Conference on Hybrid and Organic Photovoltaics
Proceedings of International Conference on Hybrid and Organic Photovoltaics (HOPV22)
València, Spain, 2022 May 19th - 25th
Organizers: Pablo Docampo, Eva Unger and Elizabeth Gibson
Oral, Dmitry Maslennikov, presentation 093
Publication date: 20th April 2022

Singlet fission (SF), which allows one singlet state to be converted to 2 triplets, is one of the most perspective phenomena that may facilitate overcoming of the Shockley-Quiser limit in organic and hybrid photovoltaics1. Yet, understanding SF intrinsic mechanism is hampered by defects and imperfections in semiconductors that may affect SF dramatically.2

In this work we applied transient absorption spectroscopy (TAS) to study SF dynamics in intrinsically defectless high quality rubrene single crystals. By accessing near infrared spectral region, we were able to clearly identify spectrally isolated features of triplet-triplet and singlet-singlet transitions. Combining ultrafast sub-10 femtosecond and nanosecond TAS allowed us to fully disentangle singlet fission mechanism and triplet’s dynamics in this material. We found that on 200fs – 6 ns timescale SF appears to be a two-step process with half of the singlets to be converted to triplets at 10ps. Remarkably, on <200fs timescale we found an additional component to be involved, which we attribute to a hybrid state facilitating SF at early times. Our exciting experimental findings allowed us to build a complete model of singlet fission in crystalline rubrene, which may help to resolve current debates on SF in the literature.

Presenting author acknowledges funding by the Imperial College London President’s PhD Scholarships.

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