Oxy Phosphorus Triazatetrabenzocorrole as a p-Type Organic Semiconductor in Organic Thin Film Transistors

Triazatetrabenzocorroles (Tbc) consist of a class of molecules derived from the phthalocyanine and porphyrin families that are less commonly synthesized and utilized in applications for organic electronics. In this work, we have synthesized oxy phosphorus Tbc (POTbc) and integrated it as an organic semiconductor in organic thin film transistors (OTFTs). Both bottom-gate bottom-contact (BGBC) and bottom-gate top-contact (BGTC) OTFTs fabricated with POTbc resulted in a clear p-type performance both in air and under inert conditions. A series of solution-based silanes and thermally evaporated p-sexiphenylene were utilized as dielectric surface treatments as a means to modify the surface energy of the dielectric surface prior to depositing the POTbc thin films. Other fabrication conditions were also explored, such as deposition rate of POTbc, substrate surface temperature during deposition, and post-deposition annealing. Of these, optimized POTbc-based OTFTs were obtained from n-octadecyltrichlorosilane (ODTS)-coated substrates, with a heated deposition, which afforded an average field effect mobility of 8.18 × 10–3 cm2 V–1 s–1 and a threshold voltage of −23.2 V. X-ray diffraction and polarized Raman microscopy indicated a significant increase in the POTbc film crystallinity and a film morphology with a more molecular face-on configuration when deposited on ODTS-treated surfaces. These results represent the first report of OTFTs fabricated using POTbc, including structure–property relationships related to thin film optimization and device performance.