Molecular Self‐Doping Controls Luminescence of Pure Organic Single Crystals |
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Authors: | Olga D Parashchuk Artur A Mannanov Vladislav G Konstantinov Dmitry I Dominskiy Nikolay M Surin Oleg V Borshchev Sergei A Ponomarenko Maxim S Pshenichnikov Dmitry Yu Paraschuk |
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Affiliation: | 1. Faculty of Physics and International Laser Center, Lomonosov Moscow State University, Moscow, Russian Federation;2. Zernike Institute for Advanced Materials, University of Groningen, Groningen, The Netherlands;3. Enikolopov Institute of Synthetic Polymeric Materials, Russian Academy of Science, Moscow, Russian Federation;4. Faculty of Chemistry, Lomonosov Moscow State University, Moscow, Russian Federation |
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Abstract: | Organic optoelectronics calls for materials combining bright luminescence and efficient charge transport. The former is readily achieved in isolated molecules, while the latter requires strong molecular aggregation, which usually quenches luminescence. This hurdle is generally resolved by doping the host material with highly luminescent molecules collecting the excitation energy from the host. Here, a novel concept of molecular self‐doping is introduced in which a higher luminescent dopant emerges as a minute‐amount byproduct during the host material synthesis. As a one‐stage process, self‐doping is more advantageous than widely used external doping. The concept is proved on thiophene–phenylene cooligomers (TPCO) consisting of four (host) and six (dopant) conjugated rings. It is shown that <1% self‐doping doubles the photoluminescence in the TPCO single crystals, while not affecting much their charge transport properties. The Monte‐Carlo modeling of photoluminescence dynamics reveals that host–dopant energy transfer is controlled by both excitonic transport in the host and host–dopant Förster resonant energy transfer. The self‐doping concept is further broadened to a variety of conjugated oligomers synthesized via Suzuki, Kumada, and Stille crosscoupling reactions. It is concluded that self‐doping combined with improved excitonic transport and host–dopant energy transfer is a promising route to highly luminescent semiconducting organic single crystals for optoelectronics. |
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Keywords: | charge transport Fö rster resonant energy transfer organic electronics Suzuki reaction thiophene– phenylene cooligomers |
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