Influence of self-assembly monolayers on the characteristics of copper phthalacyanine thin film transistor

Self-assembly monolayers (SAMs) of octadecyltrichlorosilane (OTS) on a silicon dioxide substrate were formed in solution, or by vacuum vapor methods, and characterized by Fourier transform infrared (FTIR) spectroscopy. We found that the OTS SAMs on SiO₂ substrates greatly affect the order and connectivity of evaporated copper phthalocyanine (CuPc) thin films, as confirmed by an atomic force microscopy (AFM) and X-ray diffraction analysis. The performance of the organic CuPc thin film transistor comprising OTS SAMs interposed between a gate dielectric and an organic semiconductor layer could be effectively enhanced as a result of improvements in the quality both of the organic/dielectric interface and the evaporated CuPc thin films. The deposition of an OTS SAM leads to a mobility of 1.48×10^-3 cm²/Vs, 1–2 orders higher than that of bare silicon dioxide. PACS 73.61.Ph; 85.30.Tv; 78.66.Tr