1:45 PM - 2:00 PM
[21p-W521-1] [Young Scientist Presentation Award Speech] Prospect for n-type thin film transistors using organic semiconducting molecular compounds
Keywords:charge transfer complex,n-type organic semiconductor,solution process
Most of the semiconducting charge transfer (CT) compounds are obtained, if the donor and acceptor molecules alternately stacked to form mixed-stack-type molecular packing. These compounds feature strong donor-acceptor CT interactions and a concomitant narrow CT gap energy that can be tuned by the combination of the component donor and acceptor species. Such unique characteristics are promising for providing functional organic electronics or optoelectronic devices, although studies on thin-film device applications have been limited. Because semiconducting CT compounds have a high tendency to form needle crystals along the donor-acceptor molecular stacks, manufacturing high quality thin films on substrate surfaces is difficult.
Recently, we developed semiconducting CT compounds of (diCmBTBT)(FnTCNQ) [m=4, 8, 12;n=0, 2, 4]. (diC8BTBT=2,7-dioctyl[1]benzothieno[3,2-b][1]benzothiophene and FnTCNQ = fluorinated derivatives of 7,7,8,8,-tetracyanoquinodimethane), which have a high degree of layered crystallinity. Single-phase and uniaxially oriented polycrystalline thin films of the compounds were obtained by vacuum co-evaporation of the component donor and acceptor molecules. For printed-electronics, we focused on thin-film formation of these semiconducting molecular compounds by solution process. High quality thin film composed of uniaxially-oriented single crystal domains were obtained by means of solution-coating method. Organic thin-film transistors fabricated with the compound films exhibited n-type field-effect characteristics showing an excellent stability in air. In particular, field-effect mobility along a-axis in (diC8BTBT)(F2TCNQ) thin films exhibited value comparable to bulk single crystal transistors. This is attributed to formation of channel without grain boundary and large transfer integral along a-axis. In this talk, we report development of layered-crystalline CT compounds (diC8BTBT)(FnTCNQ), its thin-film formation, and thin-film transistor characteristics.
Recently, we developed semiconducting CT compounds of (diCmBTBT)(FnTCNQ) [m=4, 8, 12;n=0, 2, 4]. (diC8BTBT=2,7-dioctyl[1]benzothieno[3,2-b][1]benzothiophene and FnTCNQ = fluorinated derivatives of 7,7,8,8,-tetracyanoquinodimethane), which have a high degree of layered crystallinity. Single-phase and uniaxially oriented polycrystalline thin films of the compounds were obtained by vacuum co-evaporation of the component donor and acceptor molecules. For printed-electronics, we focused on thin-film formation of these semiconducting molecular compounds by solution process. High quality thin film composed of uniaxially-oriented single crystal domains were obtained by means of solution-coating method. Organic thin-film transistors fabricated with the compound films exhibited n-type field-effect characteristics showing an excellent stability in air. In particular, field-effect mobility along a-axis in (diC8BTBT)(F2TCNQ) thin films exhibited value comparable to bulk single crystal transistors. This is attributed to formation of channel without grain boundary and large transfer integral along a-axis. In this talk, we report development of layered-crystalline CT compounds (diC8BTBT)(FnTCNQ), its thin-film formation, and thin-film transistor characteristics.