Journal of physical chemistry c vol:114 issue:6 pages:2730-2737
In this work, an in-depth growth study with organic vapor phase deposition of the n-type semiconductor N,N'-ditridecyl-3,4,9,10-perylenetetracarboxylic diimide (PTCDI-C-13) is presented. The organic vapor phase deposition technique allows independent control of more parameters than traditional vapor thermal evaporation, namely, not only deposition flux and substrate temperature but also chamber pressure can be changed. We study the influence of these parameters on the morphology and microstructure of PTCDI-C-13 thin films, and correlate them with electrical properties. Films of PTCDI-C-13 on SiO2 surfaces modified with poly-(alpha-methylstyrene) exhibit. Stranski-Krastanov growth. Upon increasing deposition flux, the resulting surface morphology changes from rough films, characterized by needle growth, to smoother films consisting of small, uniform grains. Notably, increasing the pressure shifts this morphology transition toward lower deposition fluxes. All X-ray reflectivity measurements are indicative of PTCDI-C13 molecules assembling in well-ordered pi-stacks parallel to the substrate. This creates the opportunity to grow PTCDI-C-13 films at conditions maximizing deposition throughput and efficiency, while maintaining the structural and thus electrical quality of the PTCDI-C-13 thin films. Electron mobilities up to 0.1 cm(2)/(Vs) have been demonstrated for a deposition rate of 6.7 angstrom/s, showing that organic vapor phase deposition is a high-throughput deposition technique for perylene diimide n-type organic semiconductors.