PDVT-10/DTCPハイブリッドフィルムにおけるメニスカスガイド協働結晶化による形態制御と高性能OFET

The meniscus-guided coating (MGC) method was used to prepare well-aligned films of hybrid systems composed of the conjugated polymer poly{3,6-dithiophen-2-yl-2,5-di(2-decyltetra-decyl)-pyrrolo[3,4-c]pyrrole-1,4-dione-alt-thienylenevinylene-2,5-yl} (PDVT-10) and a photoresponsive small molecule dopant, dithienylperfluorocyclopentene (DTCP), at various concentrations in their open-ring form (DTCP-o) or closed-ring (DTCP-c) form. The structures of the coated films were characterized with polarized optical microscopy (POM), grazing-incidence X-ray diffraction (GIXRD), and atomic force microscopy (AFM). The DTCP can undergo reversible isomerization between a more twisted open-ring form and a more conjugated closed-ring form under UV and visible light, respectively. Both DTCP isomers were found to function as morphology-modulating additives that facilitate cooperative crystallization, an effect attributed to enhanced solution-phase molecular association, which impacts the packing of the polymer film. Organic field-effect transistors (OFETs) were fabricated from these films. The DTCP-c doping progressively enhanced charge transport, reaching the highest mobility of 2.44 cm² V^-1 s^-1 at 10 wt %. Notably, 3 wt % DTCP-o, typically considered insulating molecule, increased PDVT-10 mobility from 2.12 to 3.23 cm² V^-1 s^-1. This improvement is suggested to arise from the combined effects of precise molecular alignment by the MGC method and a favorable HOMO-HOMO energy level alignment predicted by DFT, enabling cooperative charge transfer despite the nominally insulating nature of the open-ring form. The photoswitchable DTCP provides a unique opportunity to optically modulate frontier molecular orbital energy levels, thereby opening up an avenue for designing electronic devices such as photocontrollable OFETs.