Donor-acceptor polymeric inks with transition-metal dichalcogenide nanosheet suspensions for inkjet-printed thin-film transistors

This study investigates molybdenum disulfide (MoS2) suspension to enhance the charge transport properties of the donor-acceptor co-polymer (DA copolymers) semiconductor diketopyrrolopyrrole thieno[3,2-b]thiophene (DPPT-TT) for inkjet-printed thin-film transistor (TFT) fabrication. A mixture of MoS2 nanosheets mixed in the DA copolymer was developed and inkjet printed for the fabrication of TFT devices. The I-V measurements of the fabricated TFTs indicated that the addition of MoS2 suspension (0.5 wt%) into the polymer matrix resulted in the improvement of carrier mobility in both hole and electron transport, with an increase of 52 % and 130 %, respectively, compared to devices without the nanosheets. The improved electrical behavior was not entirely due to transport through the single crystal nanosheets. The introduced MoS2 nanosheets also induced strongly aggregated polymeric domains in the thin film compared to pristine films without the suspension, resulting in a high degree of molecular ordering within the polymeric film. The origin of the improved microstructure of DPPT-TT-based thin films was analyzed using AFM, UV-vis-NIR, and XRD systems. The structural results were shown to correlate with the electrical behavior, further demonstrating the efficacy of the MoS2 nanosheets on the enhancement of the TFT performance.