The meniscus-guided coating (MGC) method was used to prepare well-aligned films of hybrid systems composed of the conjugated polymer poly3, 6-dithiophen-2-yl-2, 5-di (2-decyltetra-decyl) -pyrrolo3, 4-cpyrrole-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.
Lin et al. (Wed,) studied this question.