Electronic and spin functions of pi-electron interface in organic field-effect devices

在这项研究中，场诱导电子自旋共振(FI-ESR)方法被应用于直接检测有机FET界面上的载流子自旋。获得了电荷载流子的电子态和自旋态以及局域分子取向等微观信息，这对于理解器件的功能是至关重要的。在基于噻吩基分子C8-BTBT的高迁移率薄膜晶体管中，FI-ESR提供了即使在4K下高结晶区内载流子运动的证据。在超薄聚合物晶体管中，迁移率各向异性与高分子链的单轴取向之间的关联已被阐明，而在Rubrene晶体晶体管中，界面化学处理与迁移率增强之间的关联已被揭示。此外，在高密度载流子注入中，建议在聚合物和分子FET中从有自旋的极化子交叉到无自旋的双极化子或极化子对。

In this study, field-induced electron spin resonance (FI-ESR) method is applied to directly detect the spins of charge carries at the interface of organic FETs. Microscopic information such as electronic and spin states of charge carries and local molecular orientation is obtained, which is crucial in understanding the device functions. In high-mobility thin-film transistors of a thienothiophene-based molecule C8-BTBT , FI-ESR has provided evidence for the charge carrier motion even at 4K within highly crystalline domains. Correlation between mobility anisotropy and uniaxial orientation of polymer chains has been clarified in ultrathin polymeric transistors and correlation between the interface chemical treatments and mobility enhancement has been revealed in crystalline transistors of rubrene. Further, in high-density carrier injections, crossover from polarons with spins to spinless bipolarons or polaron pairs is suggested in both polymeric and molecular FETs.