| 研究実績の概要 |
In This fiscal year, I have focused on the molecular designs that lead to effective molecular assemblies in the solid-state that exhibit high n-type organic semiconductors performances. Previously, our research group has reported a new n-type benzo[de]isoquinolino[1,8-gh]quinolinetetracarboxylic diimide (BQQDI) π-electron core, and based on this π-electron core, I investigated the functionalization of asymmetric substituents to tune the materials properties. With this strategy, we have achieved excellent electron mobility up to 1.4 cm2 V/s, and successful fabrication inch-scale single-crystalline thin films. With other effective molecular design strategies, molecular assembly of BQQDI can be tuned with balanced charge transport capabilities. The appropriate selection of substituents leads to an ideal brickwork packing structure, and the single-crystalline thin-film devices exhibit an outstanding isotropic charge transport with the highest electron mobility up to 2.3 cm2 V/s. The current results shed lights into the synthesis of future π-conjugated molecules, but more importantly, it creates a platform for future molecular designs for achieving effective charge-transport capability, as well as isotropic charge transport for high performance n-type organic semiconductors.
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| 現在までの達成度 (区分) |
現在までの達成度 (区分)
1: 当初の計画以上に進展している
理由
To investigate the experimental organic semiconductor performances, we are interested in evaluating the intrinsic electron mobilities in single-crystalline thin films. Single-crystalline thin films were fabricated using the solution-processed edge-casting method as the active layer in the bottom-gate/top-contact organic field-effect transistors. In the past year, we developed multiple high-performance n-type organic semiconductors with electron mobilities more than 1.0 cm2 V/s, and these organic semiconductors possess high solubilities and solution-processability. Some of the promising derivatives were selected to fabricate inch-scale single-crystalline thin films for practical electronic applications using the continuous edge-casting method. Using the large-area single-crystalline thin films, a large number of transistors can potentially be fabricated for constructing high-end electronics such as logic circuits and radio-frequency identification tags. In addition, we were able to confirm the electron mobilities at various angles. The derivatives with the isotropic charge transport also showed isotropic electron mobilities.
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| 今後の研究の推進方策 |
The next plan of my research project involves the molecular design of n-type organic semiconductors with two-dimensional molecular assemblies such as the herringbone and brickwork packings. The goal is to develop n-type organic semiconductors with excellent charge-transport capabilities. From our effort in the 2020 fiscal year, we developed methods to computationally predict the single crystal packing structures of organic semiconductors and their charge-transport capabilities. Using this powerful method, we are able to screen potential molecular designs with much improved efficiency, and synthetic efforts are only spent on the promising candidates. We are interested in the candidates that exhibit two-dimensional packings such as the brickwork or herringbone assemblies which usually show effective charge transports. With the current results and knowledge we have gathered, we aim to develop high-performance and solution-processable n-type organic semiconductors that exhibit electron mobilities over 5 cm2/Vs for practical electronics.
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