Temperature gradient approach to grow large, preferentially oriented 6,13-bis(triisopropylsilylethynyl) pentacene crystals for organic thin film transistors

In this study, 6,13-bis(triisopropylsilylethynyl) (TIPS) pentacene crystalline growth was enhanced using temperature gradient across the substrate. This method induced a preferential crystal orientation in order to alleviate the intrinsic crystallization anisotropy and control film morphology. The temperature gradient led to a solubility difference along the substrate and drove crystallization from the lower-temperature end to the higher. The approach also enables a methodical investigation of how TIPS pentacene crystal morphology depends on temperature. The resulting TIPS pentacene film exhibited a uniform morphology and high percentage of large areal coverage. X-ray diffraction characterization showed that the film crystallinity was not sacrificed when a temperature gradient is applied. The authors demonstrated that organic thin film transistors (OTFTs) based on TIPS pentacene crystals grown using the temperature-gradient method significantly enhanced average mobility when compared to OTFTs using films grown without the temperature gradient.