Luminescent High‐Mobility 2D Organic Semiconductor Single Crystals

Trul A.A., Chekusova V.P., Anisimov D.S., Borshchev O.V., Polinskaya M.S., Agina E.V., Ponomarenko S.A.

AbstractUltrathin organic field effect transistors (OFETs) demonstrate great potential as highly sensitive gas sensors since its electrical performance strongly depends on the environment. However, fabrication of high performance OFETs with reliable operational stability for continuous measurements by fast, rather simple, and inexpensive technique is still a challenge. Herein, electrical and sensing properties of ultrathin OFETs based on siloxane dimers of benzothieno[3,2‐b][1]benzothiophene (BTBT) with different aliphatic spacer lengths fabricated by Langmuir–Blodgett, Langmuir–Schaefer (LS) or spin‐coating techniques are studied, compared and optimized. Investigation of the influence of interface dielectric layer on electrical performance and operational stability of the devices allowed obtaining uniform low‐defect ultrathin semiconducting layers responsible for improved electrical performance. Field‐effect mobility up to 0.47 cm2 V−1 s−1 is achieved for the devices based on the dimer with undecylenic spacer between the BTBT core and disiloxane central fragment fabricated by LS method on the top of poly(methyl methacrylate) interface layer. Promising operational stability lead to advanced sensory properties demonstrated by sensing of ethanethiol with the limit of detection of 30 ppb in the humid air, which is a record value for portable sensing technologies.

Chen Y., Deng W., Zhang X., Wang M., Jie J.

Organic field-effect transistors (OFETs) have attracted intense interest due to their solution-processability, flexibility, and mechanical stretchability. Dramatic improvements have been made in the performance of OFETs, but, in reality, OFETs are usually plagued by ambient instability. This instability is strongly associated with extrinsic factors, such as the presence of moisture and oxygen. Therefore, in this review, recent studies of water- and oxygen-related instabilities in OFETs and their origins are discussed and summarized, with a particular focus on p-type OFETs. Based on this, we have focussed on the discussion of the strategies for improving the ambient stability of OFETs, particularly for those components that are most studied in this context: organic semiconductor (OSC) layers, OSC/gate dielectric interface, and OSC/electrode interface. Finally, a summary of the review, as well as a conclusion with a perspective on the pathways to further enhance the stability of OFETs, are given.

Koskin I.P., Becker C.S., Sonina A.A., Trukhanov V.A., Shumilov N.A., Kuimov A.D., Zhuravleva Y.S., Kiseleva Y.O., Shundrina I.K., Sherin P.S., Paraschuk D.Y., Kazantsev M.S.

Linearly conjugated oligomers attract ever‐growing attention as promising systems for organic optoelectronics because of their inherent lucky combination of high charge mobility and bright luminescence. Among them, furan‐phenylene co‐oligomers (FPCOs) are distinguished by outstanding solubility, very bright luminescence, and good hole‐transport properties; however, furan‐containing organic semiconductors generally lack electron transport, which makes it impossible to utilize them in efficient light‐emitting electronic devices, specifically, ambipolar light‐emitting transistors. In this work, 1,4‐bis(5‐phenylfuran‐2‐yl)benzene (FP5) derivatives are synthesized with the fully/partially fluorinated central and edge phenyl rings. It is shown that the selective fluorination of FPCOs lowers the energies of frontier molecular orbitals, maintaining the bandgap, solubility, and bright luminescence, dramatically improves the photostability, tunes the π‐π stacked packing, and allows the first realization of electron transport in FPCOs. It is found that selectively fluorinated 2,2′‐(2,3,5,6‐tetrafluoro‐1,4‐phenylene)bis[5‐(3,5‐difluorophenyl)furan] demonstrates well‐balanced ambipolar charge transport and efficient electroluminescence in an organic light‐emitting transistor (OLET) with external quantum and luminous efficiencies as high as 0.63% and 5 cdA−1, respectively, which are among the best reported for OLETs. The findings show that “smart” fluorination is a powerful tool to fine‐tune the stability and performance of linearly conjugated small molecules for organic optoelectronics.

Gierschner J., Shi J., Milián‐Medina B., Roca‐Sanjuán D., Varghese S., Park S.

Luminescent small, all‐organic molecules are of tremendous interest in materials and life science applications. Nevertheless, targeted design requires a basic understanding of the excited state deactivation pathways of the molecules themselves, and the modulations of the processes that occur in the solid state. This particularly concerns crystalline molecular solids, as here not only solid‐state rigidification contributes to these modulations, but specific intermolecular interactions as well. Starting from the molecular properties, this work carefully disentangles all intramolecular and intermolecular factors to the radiative and nonradiative processes in crystalline all‐organic molecular solids to provide guidelines for targeted molecular materials design.

Borshchev O.V., Skorotetcky M.S., Trukhanov V.A., Fedorenko R.S., Surin N.M., Svidchenko E.A., Sosorev A.Y., Kazantsev M.S., Paraschuk D.Y., Ponomarenko S.A.

Two novel organic semiconductors with tetrathienoacene (TTA) as the central core end-capped with 5-hexyl-2-thiophene, (Hex-T) 2 -TTA, and 4-hexyl-phenyl, (Hex-Ph) 2 -TTA, have been synthesized and investigated for organic field effect transistor (OFET) applications. The novel TTA derivatives were characterized by thermal gravimetric analysis, differential scanning calorimetry, UV–Vis spectroscopy, and cyclic voltammetry as well as studied by density functional theory calculations. Two types of OFETs with the solution and vacuum-deposited active layer were fabricated and characterized. Both TTA-derivatives demonstrated electroluminescence in OFETs, and (Hex-Ph) 2 -TTA showed ambipolar charge transport with the hole mobility as high as 0.68 cm 2 V −1 s −1 . • Two novel tetrathienoacene (TTA) derivatives were designed and synthesized. • The structure-property relationships were systematically investigated. • Ultrathin single crystal and polycrystalline OFETs were fabricated and characterized. • The ambipolar conductivity and electroluminescence were detected.

Prosa M., Moschetto S., Benvenuti E., Zambianchi M., Muccini M., Melucci M., Toffanin S.

The fascinating combination of light-emitting characteristics and electrical amplification identifies organic light-emitting transistors (OLETs) as key enabling devices for a wide variety of applications, ranging from displays to sensors. Pursuing a dual functionality in a single-layer architecture is the major strength and the major challenge of this technology. Limitations mainly arise from the poor availability of organic semiconductors that are able to ensure good ambipolar behavior in charge transport together with an efficient light-emission in the solid state. In this present study, we report on a new class of thienoimide-ended oligothiophenes as molecular compounds simultaneously endowed with good field-effect mobility for holes and electrons, good processability, self-assembly capability into nanostructures and remarkable properties of photo- and electroluminescence in the solid state. The versatile chemical tuning of the molecular structure and the fine use of both solution-processed and physical deposition techniques in the realization of nanostructured thin-films are the major tools for controlling the packing of molecules and their intermolecular interactions in the solid state. Indeed, the inherent polymorphism of this class of compounds is directly correlated with their electrical and optoelectronic properties as active materials in multifunctional devices. Considering the field-effect transistor as a benchmark device platform, here we propose the extended family of thienoimide-ended oligothiophenes as a case study in virtue of (i) the solid and throughout correlation of the molecular structure and solid-state organization with the figures of merit in transistor-based devices, and (ii) the possibility of engineering highly integrated planar organic optoelectronic devices with multiple functionalities for the investigation of photophysical and charge transport processes in organic compounds and, ultimately, the demonstration of real-setting applications of OLET technology.

Chaudhry M.U., Panidi J., Nam S., Smith A., Lim J., Tetzner K., Patsalas P.A., Vourlias G., Sit W., Firdaus Y., Heeney M., Bradley D.D., Anthopoulos T.D.

The vast majority of conjugated‐polymer‐based light emitting field‐effect transistors (LEFETs) are characterized by low charge‐carrier mobilities typically in the 10−5 to 10−3 cm2 V−1 s−1 range. Fast carrier transport is a highly desirable characteristic for high‐frequency LEFET operation and, potentially, for use in electrically pumped lasers. Unfortunately, high‐mobility organic semiconductors are often characterized by strong intermolecular π–π interactions that reduce luminescence. Development of new materials and/or device concepts that overcome this hurdle are therefore required. Single organic semiconductor layer based LEFETs that combine high hole mobilities with encouraging light emission characteristics are reported. This is achieved in a single polymer layer LEFET, which is further enhanced through the use of a small‐molecule/conjugated polymer blend system that possesses a film microstructure which supports enhanced charge‐carrier mobility (3.2 cm2 V−1 s−1) and promising light‐emission characteristics (1600 cd m−2) as compared to polymer‐only based LEFETs. This simple approach represents an attractive strategy to further advance the performance of solution‐processed LEFETs.

Maslennikov D.R., Sosorev A.Y., Fedorenko R.S., Luponosov Y.N., Ponomarenko S.A., Bruevich V.V.

Recently developed ultrathin two-dimensional (2D) organic semiconductor crystals are a promising platform for advanced organic electronic devices. Remarkable quality of such crystals results in charge-carrier mobilities comparable to those of bulk crystals, but their structure and orientation are hard to study because of their extremely small thickness. Here, we applied surface-enhanced Raman spectroscopy (SERS) to investigate the structure of the thinnest 2D single crystals—monolayers, which are based on thiophene-phenylene co-oligomers: 1,4-bis(5′-decyl-2,2′-bithiene-5-yl)benzene and 1,4-bis(5′-hexyl-2,2′-bithiene-5-yl)benzene. Their Raman spectra were calculated as a function of the molecule orientation and SERS microscopy maps were acquired. High sensitivity of SERS allowed us to study monolayer single-crystal domains with the optical spatial resolution. Raman anisotropy was used to probe the orientations of single-crystal domains and the molecule orientation within them. Notably, the SERS microscopy ...

Zaumseil J.

Light‐emitting field‐effect transistors (LEFETs) combine switching and amplification with light emission and thus represent an interesting optoelectronic device. They are not limited anymore to a few examples and specific materials but are nearly universal for a wide range of semiconductors, from organic to inorganic and nanoscale. This review introduces the basic working principles of lateral unipolar and ambipolar LEFETs and discusses recent examples based on various solution‐processed semiconducting materials. Applications beyond simple light emission are presented and possible future directions for light‐emitting transistors with added functionalities are outlined.

Cao M., Zhang C., Cai Z., Xiao C., Chen X., Yi K., Yang Y., Lu Y., Wei D.

Owing to strong light-matter interaction, two-dimensional (2D) organic crystal is regarded as promising materials for ultrasensitive photodetectors, however it still received limited success due to degraded photoelectrical response and problems in controllable growth. Here, we find the growth of 2D organic crystal obeys Gibbs-Curie-Wulff law, and develop a seed-epitaxial drop-casting method to grow millimeter-sized 1,4-bis(4-methylstyryl)benzene 2D crystals on SiO2/Si in a thermodynamically controlled process. On SiO2/Si, a distinct 2D limit effect is observed, which remarkably enhances internal photoresponsivity compared with bulk crystals. Experiment and calculation show the molecules stack more compactly at the 2D limit, thus better molecular orbital overlap and corresponding changes in the band structure lead to efficient separation and transfer of photo-generated carriers as well as enhanced photo-gating modulation. This work provides a general insight into the growth and the dimension effect of the 2D organic crystal, which is valuable for the application in high-performance photoelectrical devices.To realize efficient optoelectronic devices based on two-dimensional (2D) organic crystals, optimizing the photoelectrical response and growth of these materials at the 2D limit is vital. Here, the authors report enhanced internal photoresponse in large-area 2D crystals using a novel growth method.

Bruevich V.V., Glushkova A.V., Poimanova O.Y., Fedorenko R.S., Luponosov Y.N., Bakirov A.V., Shcherbina M.A., Chvalun S.N., Sosorev A.Y., Grodd L., Grigorian S., Ponomarenko S.A., Paraschuk D.Y.

High structural quality of crystalline organic semiconductors is the basis of their superior electrical performance. Recent progress in quasi two-dimensional (2D) organic semiconductor films challenges bulk single crystals because both demonstrate competing charge-carrier mobilities. As the thinnest molecular semiconductors, monolayers offer numerous advantages such as unmatched flexibility and light transparency as well  they are an excellent platform for sensing. Oligothiophene-based materials are among the most promising ones for light-emitting applications because of the combination of efficient luminescence and decent charge-carrier mobility. Here, we demonstrate single-crystal monolayers of unprecedented structural order grown from four alkyl-substituted thiophene and thiophene-phenylene oligomers. The monolayer crystals with lateral dimensions up to 3 mm were grown from the solution on substrates with various surface energies and roughness by drop or spin-casting with subsequent slow solvent evaporation. Our data indicate that 2D crystallization resulting in single-crystal monolayers occurs at the receding gas-solution-substrate contact line. The structural properties of the monolayers were studied by grazing-incidence X-ray diffraction/reflectivity, atomic force and differential interference contrast microscopies, and imaging spectroscopic ellipsometry. These highly ordered monolayers demonstrated an excellent performance in organic field-effect transistors approaching the best values reported for the thiophene or thiophene-phenylene oligomers. Our findings pave the way for efficient monolayer organic electronics highlighting the high potential of simple solution-processing techniques for the growth of large-size single-crystal monolayers with excellent structural order and electrical performance competing against bulk single crystals.

Mannanov A.A., Kazantsev M.S., Kuimov A.D., Konstantinov V.G., Dominskiy D.I., Trukhanov V.A., Anisimov D.S., Gultikov N.V., Bruevich V.V., Koskin I.P., Sonina A.A., Rybalova T.V., Shundrina I.K., Mostovich E.A., Paraschuk D.Y., et. al.

Long-range exciton diffusion facilitates efficient exciton harvesting in a lightly-doped organic semiconductor crystal.

Trukhanov V.A., Bruevich V.V., Paraschuk D.Y.

The crucial parameter that determines the performance of a semiconductor material in organic field-effect transistors (OFETs) is the charge carrier mobility. The conventional method of its determination based on Shockley’s equations can lead to incorrect mobility evaluation due to contact effects. Particularly, in the common staggered OFET architecture (top-contact bottom-gate or bottom-contact top-gate), the space-charge limited current (SCLC) effect in the active layer under/above the source and drain contacts decreases the source-drain current. In this work, we model the effect of SCLC under/above the source and drain electrodes on the OFET apparent mobility (i.e., calculated from the device characteristics) and apparent threshold voltage for different active layer thickness and intrinsic mobility anisotropy. For the saturation regime, we derived simple analytical expressions for transfer characteristics and apparent mobility. Our modeling shows that the apparent OFET mobility is more than five times lower than the intrinsic one for the active layer thicker than 100 nm with mobility anisotropy (along vs across the active layer) higher than 100. While the SCLC effect does not change the apparent threshold voltage, it reveals itself as a kink at near zero voltage in the output characteristics. The proposed model gives analytical expressions for the transfer characteristics and apparent mobility as explicit functions of the intrinsic mobility and the device parameters in the saturation regime and as implicit functions in the linear regime. Our findings provide guidelines for accurate evaluation of the intrinsic mobility in OFETs fabricated in the staggered architecture and for further improvement of OFET performance.

Liu C., Liu X., Lai W., Huang W.

Organic light‐emitting transistors (OLETs), as novel and attractive kinds of organic electronic devices, have gained extensive attention from both academia and industry. The unique device architectures can simultaneously combine the electrical switching functionality of organic field‐effect transistors and the light generation capability of organic light‐emitting diodes in a single device, thereby holding great promise for reducing the complicated processes of next‐generation pixel circuitry. This review involves the design, fabrication, and applications of OLETs with a comprehensive coverage of this field with the aim to give a deep insight into the intrinsic mechanisms of devices. Challenges and future prospects of OLETs are also discussed.

Paterson A.F., Singh S., Fallon K.J., Hodsden T., Han Y., Schroeder B.C., Bronstein H., Heeney M., McCulloch I., Anthopoulos T.D.

Over the past three decades, significant research efforts have focused on improving the charge carrier mobility of organic thin‐film transistors (OTFTs). In recent years, a commonly observed nonlinearity in OTFT current–voltage characteristics, known as the “kink” or “double slope,” has led to widespread mobility overestimations, contaminating the relevant literature. Here, published data from the past 30 years is reviewed to uncover the extent of the field‐effect mobility hype and identify the progress that has actually been achieved in the field of OTFTs. Present carrier‐mobility‐related challenges are identified, finding that reliable hole and electron mobility values of 20 and 10 cm2 V−1 s−1, respectively, have yet to be achieved. Based on the analysis, the literature is then reviewed to summarize the concepts behind the success of high‐performance p‐type polymers, along with the latest understanding of the design criteria that will enable further mobility enhancement in n‐type polymers and small molecules, and the reasons why high carrier mobility values have been consistently produced from small molecule/polymer blend semiconductors. Overall, this review brings together important information that aids reliable OTFT data analysis, while providing guidelines for the development of next‐generation organic semiconductors.

Levkov L.L., Surin N.M., Borshchev O.V., Titova Y.O., Dubinets N.O., Svidchenko E.A., Shaposhnik P.A., Trul A.A., Umarov A.Z., Anokhin D.V., Rosenthal M., Ivanov D.A., Ivanov V.V., Ponomarenko S.A.

Organic semiconductor materials are interesting due to their application in various organic electronics devices. [1]benzothieno[3,2-b][1]benzothiophene (BTBT) is a widely used building block for the creation of such materials. In this work, three novel solution-processable regioisomeric derivatives of BTBT—2,7-bis(3-octylthiophene-2-yl)BTBT (1), 2,7-bis(4-octylthiophene-2-yl)BTBT (2), and 2,7-bis(5-octylthiophene-2-yl)BTBT (3)—were synthesized and investigated. Their optoelectronic properties were characterized experimentally by ultraviolet–visible and fluorescence spectroscopy, time-resolved fluorimetry, and cyclic voltammetry and studied theoretically by Time-Dependent Density Functional Theory calculations. Their thermal properties were investigated by a thermogravimetric analysis, differential scanning calorimetry, polarizing optical microscopy, and in situ small-/wide-angle X-ray scattering measurements. It was shown that the introduction of alkyl substituents at different positions (3, 4, or 5) of thiophene moieties attached to a BTBT fragment significantly influences the optoelectronic properties, thermal stability, and phase behavior of the materials. Thin films of each compound were obtained by drop-casting, spin-coating and doctor blade techniques and used as active layers for organic field-effect transistors. All the OFETs exhibited p-channel characteristics under ambient conditions, while compound 3 showed the best electrical performance with a charge carrier mobility up to 1.1 cm2·V−1s−1 and current on/off ratio above 107.

Kuevda A.V., Espinoza Cangahuala M.K., Hildner R., Jansen T.L., Pshenichnikov M.S.

Wu T., Tan L., Feng Y., Zheng L., Li Y., Sun S., Liu S., Cao J., Yu Z.

Sonina A.A., Cheshkina D.S., Kazantsev M.S.

Charushin Valery N., Verbitskiy Egor V., Chupakhin Oleg N., Vorobyeva Daria V., Gribanov Pavel S., Osipov Sergey N., Ivanov Andrey V., Martynovskaya Svetlana V., Sagitova Elena F., Dyachenko Vladimir D., Dyachenko Ivan V., Krivokolysko Sergey G., Dotsenko Viktor V., Aksenov Aleksandr V., Aksenov Dmitrii A., et. al.

The chemistry of heterocyclic compounds has traditionally been and remains a bright area of chemical science in Russia. This is due to the fact that many heterocycles find the widest application. These compounds are the key structural fragments of most drugs, plant protection agents. Many natural compounds are also derivatives of heterocycles. At present, more than half of the hundreds of millions of known chemical compounds are heterocycles. This collective review is devoted to the achievements of Russian chemists in this field over the last 15–20 years. The review presents the achievements of leading heterocyclists representing both RAS institutes and university science. It is worth noting the wide scope of the review, both in terms of the geography of author teams, covering the whole of our large country, and in terms of the diversity of research areas. Practically all major types of heterocycles are represented in the review. The special attention is focused on the practical applications of heterocycles in the design of new drugs and biologically active compounds, high-energy molecules, materials for organic electronics and photovoltaics, new ligands for coordination chemistry, and many other rapidly developing areas. These practical advances would not be possible without the development of new fundamental transformations in heterocyclic chemistry.The bibliography includes 2237 references.

Maslennikov D.R., Dominskiy D.I., Sosorev A.Y., Trukhanov V.A., Konstantinov V.G., Sorokina N.I., Borshchev O.V., Skorotetcky M.S., Ponomarenko S.A., Paraschuk D.Y.

Наумов А.В., Уточникова В.В.

С 23 по 26 апреля 2024 года в Москве прошла Всероссийская конференция с международным участием LUMOS‑2024, посвященная теоретическим и практическим аспектам явления люминесценции (https://lumos‑2024.ru/). Головным организатором мероприятия выступили Химический факультет и Факультет наук о материалах МГУ им. М. В. Ломоносова при активном участии Российской академии наук.

Sosorev A.Y.

For efficient operation of many organic electronic devices, organic semiconductors with high charge carrier mobility are required. However, in most of the known organic semiconductors, the charge mobility is low, since it is limited by the strong local electron-phonon interaction. In the present work, using the example of thiophene-phenylene co-oligomers, a class of organic semiconductors that combine a sufficiently high charge mobility with light emission and therefore promising for light-emitting transistors and electrically pumped lasers, the mechanism of suppression of the electron-phonon interaction by introducing electronegative atoms or an additional thiophene ring is studied. It was found that such structural changes alter the contribution of various vibrational modes to the local electron-phonon interaction, in particular, to the suppression of the contribution of the low-frequency torsion mode. In addition, it is shown that for the two modes that make the largest contribution to the local electron-phonon interaction in an unsubstituted oligomer, this change correlates with their intensity of Raman scattering, and this confirms the promise of studying the electron-phonon interaction using Raman spectroscopy. The results obtained improve the understanding of the relationship between the local electron-phonon interaction and the molecular structure of organic semiconductors, which is extremely important for the directed design of such materials with high charge mobility.

Korchkova S.N., Sosorev A.Y.

Organic light-emitting transistors are a new type of optoelectronic devices that combine the functionality of OLED and a transistor that controls it. The working layer of these devices requires organic semiconductors that combine high charge mobility with a high photoluminescence quantum yield. One of the promising classes of such materials are thiophene-phenylene co-oligomers, the properties of which can be tuned over a wide range by adding various substituents. In this work, we address the effect of fluorination on the properties of two model thiophene-phenylene co-oligomers with an annulated central fragment, P–TTA–P and P–BTBT–P. It is shown that fluorination of both molecules lowers their frontier orbitals energy levels, and this should enable electron transport in their crystals and films. At the same time, fluorination has a qualitatively different effect on the delocalization of frontier orbitals, the width of the optical gap, the oscillator strength, the exciton binding energy, and the Raman spectrum, which is explained by the difference in the equilibrium geometry of fluorinated molecules. It is expected that the revealed relationships between the structure and properties of the studied compounds will contribute to the rational design of organic semiconductors for efficient light emitting devices.

Sosorev A.Y., Vener M.V., Kharlanov O.G., Feldman E.V., Borshchev O.V., Sorokina N.I., Rybalova T.V., Ponomarenko S.A., Paraschuk D.Y.

Feriancová L., Balakirev D.O., Fedorenko R.S., Kuevda A.V., Trukhanov V.A., Svidchenko E.A., Surin N.M., Peregudova S.M., Dmitryakov P.V., Dubinets N.O., Fedorov Y.V., Putala M., Ponomarenko S.A., Paraschuk D.Y., Luponosov Y.N.

Thiophene-phenylene co-oligomers (TPCOs) have shown their high potential for organic light-emitting devices because of their high luminescence and efficient charge transport. However, unsubstituted TPCOs have relatively wide optical bandgaps and the high-lying lowest unoccupied molecular orbital (LUMO) energies so that efficient electron transport is a challenge. Electron-withdrawing groups (EWGs) and fluorinated fragments embedded into the TPCO molecule structure could result in the lower LUMO energy and narrower optical bandgap. Here, we report the synthesis of two novel TPCOs series with either phenylene or perfluorinated phenylene central core and end-capped with various EWGs (aldehyde, 2-ethylhexyl cyanoacetate, hexyl rhodanine and dicyanorhodanine) and with long alkyl terminal and side chains increasing the solubility. All the oligomers synthesized were found to be thermally stable and crystalline materials with relatively low LUMO energies (down to −3.50 eV), narrow bandgaps (down to 1.9 eV), and efficient photoluminescence in the green – deep red spectral regions both in solution and solid-state. The TPCOs with 2-ethylhexyl cyanoacetate EWG were crystallized in large-area single-crystal monolayers, which showed strongly polarized photoluminescence and demonstrated their high potential as active layers in solution-processed single-layer organic light-emitting transistors.

Trukhanov V.A., Kuevda A.V., Dominskiy D.I., Mannanov A.L., Rybalova T.V., Tafeenko V.A., Sosorev A.Y., Konstantinov V.G., Kazantsev M.S., Borshchev O.V., Ponomarenko S.A., Pshenichnikov M.S., Paraschuk D.Y.

Highly emissive organic semiconductor that supports the combination of balanced ambipolar charge transport, weakened light waveguiding, and strongly polarized surface electroluminescence in organic light-emitting transistors is reported.

Sosorev A.Y., Dominskiy D.I., Dubinets N.O.

Luminophores featuring thermally activated delayed fluorescence (TADF) are the workhorses of the third- and fourth-generation OLEDs. While these compounds have usually been used as dopants embedded in the host, non-doped TADF OLEDs have recently shown significant progress as well and have attained performances comparable to those of the host-dopant systems. For efficient operation of non-doped OLEDs, the charge transport in neat films and single crystals of TADF luminophores is important; however, this issue was nearly unexplored theoretically. In the current study, we calculated the charge-carrier mobilities in four single crystals of TADF luminophores that have different molecular packing motifs. Specifically, in one of them both the donor and acceptor moieties form uniform π-stacks, while in the others the donors (acceptors) show alternating lateral shifts along the stacks; the difference in the molecular packing resulted in the difference in the transfer integrals between the molecules. The reorganization energies differed as well by up to four times for the studied crystals. As a result, the charge mobilities varied from 0.001 to ~0.3 cm2/(V∙s), with the largest being predicted for the crystal of the luminophore that consisted of a rigid donor and acceptor. We anticipate that the results obtained will be useful in the design of TADF luminophores for non-doped OLEDs, OLETs, and other organic light-emitting devices.

Fedorenko R.S., Kuevda A.V., Trukhanov V.A., Sosorev A.Y., Bakirov A.V., Dorokhov A.I., Surin N.M., Borshchev O.V., Ponomarenko S.A., Paraschuk D.Y.

Photo/electroluminescent and semiconductor properties of macroscopic 2D single crystals are presented, and the impact of phenylene insertion is investigated.

Kuimov A.D., Becker C.S., Shumilov N.A., Koskin I.P., Sonina A.A., Komarov V.Y., Shundrina I.K., Kazantsev M.S.

Combination of Suzuki cross-coupling and McMurrey reactions yielded materials with controllable molecular self-doping and luminescence.