Аннотация:Emerging organic light-emitting electronic devices such as organic light-emitting transistors and lasers need materials combining high luminescence and efficient charge transport1. Doping of the materials by highly luminescent molecules is an efficient approach to control and enhance the material luminescence2. Here, we introduce the concept of self-doping according to which a higher luminescent dopant emerges as a byproduct in the course of the host material synthesis, and demonstrate how the dopant controls the luminescent and charge transfer properties of organic semiconductor crystals3.
As the host material, we synthesized thiophene(T)-phenylene(P) co-oligomer (TPCO) with the conjugated core P2TP and trimethylsilyl end group. We have grown series of P2TP single crystals with various concentration of the self-dopant with the conjugated core P4TP by the solvent-antisolvent crystallization method, where the crystals are grown on the surface of solution. The crystal lateral size was about several millimeters with the dopant concentration varying from the 0.01% to 3% We show that the self-dopant P4TP present in the synthesized host (P2TP) with a concentration of ~1% doubles the photoluminescence (PL) in the TPCO single crystals, while lowering the charge mobility less than four times. PL in the self-doped single crystals is controlled by Förster resonant energy transfer from the host to the higher luminescent TPCO dopant3. We conclude that self-doping is a promising route to control and enhance the luminescent properties of organic semiconductor materials, while not hindering much their charge transport properties.
[1] L. Kudryashova et al., ACS Applied Materials & Interfaces, 2016, 8(16), 10088-10092.
[2] H. Nakanotani et al., Advanced Optical Materials, 2013, 1, 422.
[3] O. Parashchuk et al., Advanced Functional Materials, 2018, 1800116.
Acknowledgments: This work was supported by Russian Science Foundation (project № 18-12-00499).