Facile Blending Strategy for Boosting the Conjugated Polymer Semiconductor Transistor's Mobility.

The optimization of field-effect mobility in polymer field-effect transistors (FETs) is a critical parameter for advancing organic electronics. Today, many challenges still persist in understanding the roles of the design and processing of semiconducting polymers toward electronic performance. To address this, a facile approach to solution processing using blends of PDPP-TVT and PTPA-3CN is developed, resulting in a 3.5-fold increase in hole mobility and retained stability in electrical performance over 3 cm2 V-1 s-1 after 20 weeks. The amorphous D-A conjugated structure and strong intramolecular polarity of PTPA-3CN are identified as major contributors to the observed improvements in mobility. Additionally, the composite analysis by X-ray photoelectron spectroscopy (XPS) and the flash differential scanning calorimetry (DSC) technique showed a uniform distribution and was well mixed in binary polymer systems. This mobility enhancement technique has also been successfully applied to other polymer semiconductor systems, offering a new design strategy for blending-type organic transistor systems. This blending methodology holds great promise for the practical applications of OFETs.

Donor-Acceptor Effect of Carbazole-Based Conjugated Polymer Electrets on Photoresponsive Flash Organic Field-Effect Transistor Memories.

The molecular structure of polymer electrets is crucial for creating diverse functionalities of organic field-effect transistor (OFET) devices. Herein, a conceptual framework has been applied in this study to design the highly photoresponsive carbazole-based copolymer electret materials for the application of photoresponsive OFET memory. As an electret layer, two 1,8-carbazole-based copolymers were utilized; the copoly(CT) consisted of carbazole as the donor group and thiophene as the π-spacer, whereas the copoly(CBT) was further introduced as an acceptor moiety, benzothiadiazole, for comparison. Both copolymers exhibited efficient visible-light absorption and photoluminescence quenching in the film state, indicating the formation of a considerable number of nonemissive excitons, one of the crucial factors for achieving photoinduced recovery behavior in OFET memories. Compared to copoly(CT) with the pure donor system, faster and more effective photoinduced recovery behavior was discovered in the copoly(CBT) with the conjugated donor-acceptor structure because of the coexistence of the conjugated donor and acceptor groups. Thus, the dissociation of the generated excitons facilitated the stimulating of the unique ambipolar trapping property, resulting in the high-density data storage devices with multilevel current states. In addition, the nonvolatile and durable characteristics demonstrated the feasibility in application of memory and photorecorders.