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Impact of Energetically Engineered Dielectrics on Charge Transport in Vacuum-Deposited Bis(triisopropylsilylethynyl)pentacene

Kim, Se Hyun, Lee, Junghwi, Park, Namwoo, Min, Honggi, Park, Han Wool, Kim, Do Hwan, Lee, Hwa Sung
The Journal of Physical Chemistry C 2015 v.119 no.52 pp. 28819-28827
crystal structure, dielectrics, electric power, electrical properties, hysteresis, silica, solvent drying, transistors
The surface functionality of the gate dielectrics is one of the important variables to have a huge impact on the electrical performance of organic field-effect transistors (OFETs). Here, we describe the impact of energetically engineered dielectrics on charge transport in vacuum-deposited 6,13-bis(triisopropylsilylethynyl)pentacene (TIPS-pentacene) thin films for eventually realizing high-performance OFETs. A variety of self-assembled monolayers (SAMs) bearing amino, methyl, phenyl (PTS), or fluoro end groups were introduced onto the SiO₂ dielectric surfaces to design energetically engineered surfaces that can be used to explore the impact of surface functionalities at a TIPS-pentacene/gate dielectric interface. The solvent-free vacuum deposition of TIPS-pentacene was used to exclude solution-processing effects resulting from fluid flows and solvent drying processes. The TIPS-pentacene layer on the PTS-SAM yielded the best morphological and crystalline structures, which directly enhanced the electrical properties, exhibiting field-effect mobilities as high as 0.18 cm²/(V s). Furthermore, the hysteresis, turn-on voltage, and threshold voltage were correlated with the surface potentials of various SAM-dielectrics. We believe that systematic investigation of the energetically engineered dielectrics presented here can provide a meaningful step toward optimizing the organic semiconductor/dielectric interface, thereby implementing flexible and high-performance OFETs.