Surface-induced highly oriented perylo[1,12-b,c,d]selenophene thin films for high performance organic field-effect transistors

• Epitaxial crystallization of PESE on highly oriented PE substrate.
• The different PESE crystalline morphologies due to different substrate temperatures.
• The different electrical characteristics depend on different crystalline morphologies.
• The mobility is 2 orders higher than the unoriented film transistors.

Epitaxial crystallization of perylo[1,12-b,c,d]selenophene (PESE) on highly oriented polyethylene (PE) substrate through vapor phase deposition has been achieved. Oriented PESE crystals with different crystalline morphologies can be fabricated by changing the temperature of PE substrate during vacuum evaporation. When the PE substrate temperature is lower than 70 °C, sparsely dispersed PESE lathlike crystals are produced with their long axis preferentially aligned perpendicular to the chain direction of PE crystals. While the close films of PESE with lathlike crystals aligned with long axis parallel to the chain direction of PE film were obtained above 90 °C. Transistors based on expitaxially crystallized PESE films have been fabricated and the transistor properties were also studied. It is found that transistors show different electrical characteristics depending on the preparation conditions of expitaxially crystallized PESE films. The transistors based on the PESE/PE-SiO2/Si with PESE deposited on oriented PE film at low temperature, i.e., <70 °C, display a similar poor properties with the PESE/OTS-SiO2/Si type transistors. However, when the deposition temperature was elevated to 90 °C, the transistors exhibit a maximum field-effect mobility of 4.4 × 10−2 cm2 V−1 s−1 and maximum on/off ratio of 2.0 × 105, which are about 2 orders of magnitudes higher than the PESE/OTS-SiO2/Si based transistors.

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