Spin-Relaxation Mechanisms in Doped Rubrene Thin-Film Crystals
Final Report Abstract
This project aimed to analyze spin transport in electrically doped rubrene thin-film crystals within vertical device structures and to unravel the relationship between charge carrier and spin transport in this material system. Using electron spin resonance (ESR) spectroscopy at our collaboration partner's lab at the University of Cambridge, we investigated the spin relaxation time constants as well as the spin susceptibility as functions of temperature, charge carrier density, and dopant density. Doping provides an efficient way to generate charge carriers, and their high out-ofplane mobility, originating from band-like transport in the triclinic rubrene thin films, serves as a foundation for long spin diffusion lengths. By combining ESR with impedance spectroscopy and charge transport studies, we determined the spin diffusion length to be approximately 200 nm, which is comparable to the dimensions of the devices. Notably, we show that spin relaxation is governed by interactions with the dopants, and the spin coherence time increases with higher dopant concentrations due to stronger coupling between spins and dopants. This finding provides a guideline for designing optimal host-dopant systems for efficient spin transport.
Publications
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Organic permeable base transistors for high-performance photodetection with photo-memory effect. Nature Photonics, 19(10), 1088-1098.
Schröder, Jonas; Bonil, Amric; Winkler, Louis Conrad; Frede, Jan; Darbandy, Ghader; Wang, Juan; Leo, Karl; Kleemann, Hans & Benduhn, Johannes
