Temperature dependence of bis(triisopropylsilylethynyl)-pentacene nanofilm deposited on octadecyltrichlorosilane self assembled monolayer surface as a transistor channel.

: Highly pure 6,13-bis(triisopropylsilylethynyl)pentacene (TIPS-PEN) nanofilms were deposited on a hydrophobic OTS-SAM surface at two different substrate temperatures (70 degrees C and 90 degrees C) via the vacuum thermal evaporation (VTE) method. X-ray reflectivity measurements over a wide temperature range (30 degrees C-284 degrees C) revealed that out-of-plane crystallinity of the film (approximately 10 nm) remains intact but in-plane crystallinity starts to become poor from approximately 100 degrees C, and to become much more worse from 260 degrees C. Atomic force microscope images showed that TIPS-PEN films (approximately 55 nm) prepared at the substrate temperature of 90 degrees C or above commonly have a number of huge cracks between enormous crystal domains (up to 3 microm) whereas the films didn't form such morphology below T(s) = 90 degrees C. These results clearly suggest that an optimum substrate temperature of TIPS-PEN nanofilms on OTS-SAM surface must be somewhere between 70 degrees C and 90 degrees C, and the process temperature must be kept below 90 degrees C in order to form and maintain a highly crystalline film for an organic thin film transistor device since in-plane crystallinity of a semiconductor channel deeply affects the performance of a transistor.