Vladislav G. Konstantinov

Highly-emissive solution-grown furan/phenylene co-oligomer single crystals

Solution-processed furan/phenylene co-oligomer single crystals combine high photoluminescence quantum yield (>65%) and efficient charge transport (mobility 0.12 cm2 V−1 s−1) making them promising materials for printable organic optoelectronics.

Luminescent Organic Semiconducting Langmuir Monolayers

In recent years, monolayer organic field-effect devices such as transistors and sensors have demonstrated their high potential. In contrast, monolayer electroluminescent organic field-effect devices are still in their infancy. One of the key challenges here is to create an organic material that self-organizes in a monolayer and combines efficient charge transport with luminescence. Herein, we report a novel organosilicon derivative of oligothiophene-phenylene dimer D2-Und-PTTP-TMS (D2, tetramethyldisiloxane; Und, undecylenic spacer; P, 1,4-phenylene; T, 2,5-thiophene; TMS, trimethylsilyl) that meets these requirements. The self-assembled Langmuir monolayers of the dimer were investigated by steady-state and time-resolved photoluminescence spectroscopy, atomic force microscopy, X-ray reflectometry, and grazing-incidence X-ray diffraction, and their semiconducting properties were evaluated in organic field-effect transistors. We found that the best uniform, fully covered, highly ordered monolayers were semiconducting. Thus, the ordered two-dimensional (2D) packing of conjugated organic molecules in the semiconducting Langmuir monolayer is compatible with its high-yield luminescence, so that 2D molecular aggregation per se does not preclude highly luminescent properties. Our findings pave the way to the rational design of functional materials for monolayer organic light-emitting transistors and other optoelectronic devices.

Methyl substituent effect on structure, luminescence and semiconducting properties of furan/phenylene co-oligomer single crystals

Single crystals of furan/phenylene co-oligomers are among the most promising highly-emissive materials for applications in various optoelectronic devices. In this work, we synthesized and studied furan/phenylene co-oligomers with the same conjugated core 1,4-bis(5-phenylfuran-2-yl)benzene and methyl substituents at p- and m-positions of the terminal phenyls. The effect of substituents on the crystal packing, charge transport and luminescence of the single crystals was studied. Compared to the unsubstituted compound, the methyl-substituted co-oligomers demonstrated improved thermostability and enhanced photoluminescence, which we assign to J-aggregation resulting from the strong inclination of the molecules against the main crystal facet. The charge mobility in single crystal organic field-effect transistors decreased upon the inclination of the molecules. We conclude that the molecular tilt angle, intermolecular distances and interactions in crystals of heteroaryl-containing linear conjugated oligomers can be controlled by the introduction of end methyl groups in the appropriate positions.

Long-Range Exciton Transport in Brightly Fluorescent Furan/Phenylene Co-oligomer Crystals

The design of light-emitting crystalline organic semiconductors for optoelectronic applications requires a thorough understanding of the singlet exciton transport process. In this study, we show that the singlet exciton diffusion length in a promising semiconductor crystal based on furan/phenylene co-oligomers is 24 nm. To achieve this, we employed the photoluminescence quenching technique using a specially synthesized quencher, which is a long furan/phenylene co-oligomer that was facilely implanted into the host crystal lattice. Extensive Monte-Carlo simulations, exciton–exciton annihilation experiments and numerical modelling fully supported our findings. We further demonstrated the high potential of the furan/phenylene co-oligomer crystals for light-emitting applications by fabricating solution-processed organic light emitting transistors.

CCDC 1520469: Experimental Crystal Structure Determination

Related Article: Maxim S. Kazantsev, Alina A. Beloborodova, Ekaterina S. Frantseva, Tatyana V. Rybalova, Vladislav G. Konstantinov, Inna K. Shundrina, Dmitry Yu. Paraschuk, Evgeny A. Mostovich|2017|CrystEngComm|19|1809|doi:10.1039/C6CE02565J

CCDC 1520470: Experimental Crystal Structure Determination

Related Article: Maxim S. Kazantsev, Alina A. Beloborodova, Ekaterina S. Frantseva, Tatyana V. Rybalova, Vladislav G. Konstantinov, Inna K. Shundrina, Dmitry Yu. Paraschuk, Evgeny A. Mostovich|2017|CrystEngComm|19|1809|doi:10.1039/C6CE02565J