Early-stage growth observations of orientation-controlled vacuum-deposited naphthyl end-capped oligothiophenes

We report on the real-time structure formation and growth of two thiophene-based organic semiconductors, $5,{5}^{\ensuremath{'}}$-bis(naphth-2-yl)-$2,{2}^{\ensuremath{'}}$-bi- $5,{5}^{\ensuremath{'}\ensuremath{'}}$-bis(naphth-2-yl)-$2,{2}^{\ensuremath{'}}$:${5}^{\ensuremath{'}},{2}^{\ensuremath{'}\ensuremath{'}}$-terthiophene (NaT2 NaT3), studied in situ during vacuum deposition by grazing-incidence x-ray diffraction supported atomic force microscopy photoabsorption spectroscopy measurements corresponding ex samples. On device-relevant silicon dioxide substrates, for both molecules is observed to transition from two-dimensional (2D) layer-by-layer three-dimensional (3D) after a few-molecule-thick wetting layer. The crystal NaT2 film considerably more ordered than NaT3 counterpart, there significant collective change unit cell initial stage growth, indicating strain relief substrate induced as transitions three dimensions. In addition, orientation are controlled employing substrates horizontally vertically oriented few-layer molybdenum disulfide. Both form needle-like crystals ${\mathrm{MoS}}_{2}$ layers, while tall, isolated islands layers. standing ${\mathrm{MoS}}_{2}$, but lying flat ${\mathrm{MoS}}_{2}$. These results demonstrate importance film-substrate interactions thin-film microstructure naphthyl-terminated oligothiophenes.