The University of Tokyo · Engineering
Professor Jun Takeya's research lab specializes in the development of high-performance organic semiconductors and field-effect transistors, focusing on molecular design, crystal engineering, and interface optimization to achieve exceptional carrier mobility. The lab pioneers the synthesis of novel organic semiconductors—such as N-shaped and V-shaped molecules—engineered for high mobility, thermal stability, and solution processability. Key research directions include the growth of wafer-scale single crystals, the integration of high-mobility organic semiconductors with charge-transport enhancers (e.g., F4-TCNQ), and the fundamental understanding of carrier transport mechanisms in organic field-effect transistors via advanced electrical characterization. The lab’s work bridges molecular design with device physics to enable next-generation flexible and high-speed organic electronics.
Figures are computed from collected data and may differ slightly.
Very high-mobility organic transistors are fabricated with purified rubrene single crystals and high-density organosilane self-assembled monolayers. The interface with minimized surface levels allows carriers to distribute deep into the crystals by more than a few molecular layers under weak gate electric fields, so that the inner channel plays a significant part in the transfer performance. With the in-crystal carriers less affected by scattering mechanisms at the interface, the maximum transis
Two-dimensional (2D) layered semiconductors are a novel class of functional materials that are an ideal platform for electronic applications, where the whole electronic states are directly modified by external stimuli adjacent to their electronic channels. Scale-up of the areal coverage while maintaining homogeneous single crystals has been the relevant challenge. We demonstrate that wafer-size single crystals composed of an organic semiconductor bimolecular layer with an excellent mobility of 1
N-shaped organic semiconductors are synthesized via four steps from a readily available starting material. Such semiconductors exhibit preferable ionization potential for p-type operation, thermally stable crystalline phase over 200 °C, and high carrier mobility up to 16 cm(2) V(-1) s(-1) (12.1 cm(2) V(-1) s(-1) on average) with small threshold voltages in solution-crystallized field-effect transistors.
V-shaped organic semiconductors have been designed and synthesized via a large-scale applicable synthetic route. Solution-crystallized films based on such molecules have demonstrated high-performance transistor properties with maximum mobilities of up to 9.5 cm(2) V(-1) s(-1) as well as pronounced thermal durability of up to 150 °C inherent in the V-shaped cores.
Gate-voltage dependence of carrier mobility is measured in high-performance field-effect transistors of rubrene single crystals by simultaneous detection of the longitudinal conductivity sigma(square) and Hall coefficient R(H). The Hall mobility mu(H) (identical with sigma(square)R(H)) reaches nearly 10 cm(2)/V s when relatively low-density carriers (<10(11) cm(-2)) distribute into the crystal. mu(H) rapidly decreases with higher-density carriers as they are essentially confined to the surface a
High-mobility solution-processed organic transistors are developed based on a hybrid of solution-crystallized air-stable organic semiconductor 2,7-dioctyl[1]benzothieno[3,2-b][1] benzothiophene (C8- BTBT) and 2,3,5,6-tetrafluoro-7,7,8,8-tetracyanoquinodimethane (F4-TCNQ) top layers. Charge mobility as high as 6 cm2/Vs is achieved, owing to the almost perfectly periodic crystal packing and efficient charge supply from the acceptor.
High-mobility and air-stable n-type organic field transistors based on solution-crystallized N,N′-1H,1H-perfluorobutyldicyanoperylene carboxydi-imide (PDIF- CN2) are developed. Electron mobility as high as 1.3 cm2 V−1 s−1 is achieved owing to the almost-perfect periodic crystal packing.
Abstract Although high carrier mobility organic field‐effect transistors (OFETs) are required for high‐speed device applications, improving the carrier mobility alone does not lead to high‐speed operation. Because the cut‐off frequency is determined predominantly by the total resistance and parasitic capacitance of a transistor, it is necessary to miniaturize OFETs while reducing these factors. Depositing a dopant layer only at the metal/semiconductor interface is an effective technique to reduc
Recent progress in the development of organic semiconductor materials has improved the performance of both p‐ and n‐type transistors. Currently, it is anticipated that the next step in the evolution of electronics will be to establish a reliable fabrication technique for integrated electronic devices such as plastic sensor films and radio‐frequency identification (RFID) tags. Herein, a new fabrication process to grow line‐shaped organic single‐crystalline films with widths on the order of one mm
Abstract To achieve semiconducting materials with high electron mobility in organic field‐effect transistors (OFETs), low‐lying energy levels (the highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital (LUMO)) and favorable molecular packing and ordering are two crucial factors. Here, it is reported that the incorporation of pyridine and selenophene into the backbone of a diketopyrrolopyrrole (DPP)‐based copolymer produces a high‐electron‐mobility semiconductor, PD
High-speed, flexible organic field-effect transistors with a 3D structure are fabricated on a plastic substrate in which vertical channels are formed to realize high response speed. With the benefit of short channel lengths, the fabricated transistors show fast dynamic switching within 250 ns, which corresponds to 4 MHz operation, even with the modest carrier mobility of 0.2 cm2 V−1 s−1 in organic semiconductors deposited on the vertical sidewalls.
Thin film transistors (TFTs) are indispensable building blocks in any electronic device and play vital roles in switching, processing, and transmitting electronic information. TFT fabrication processes inherently require the sequential deposition of metal, semiconductor, and dielectric layers and so on, which makes it difficult to achieve reliable production of highly integrated devices. The integration issues are more apparent in organic TFTs (OTFTs), particularly for solution-processed organic
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