Cu-Thienoquinone Charge-Transfer Complex: Synthesis, Characterization, and Application in Organic Transistors

A facile and unusual reaction between thienoquinone compound QDTBDT2C and copper is reported. The formation of Cu-QDTBDT2C complex is proved by absorption spectra, IR spectra, Raman spectra, and X-ray photoelectron spectroscopy data. This complex can serve as a doping layer at the interface of Cu/QDTBDT2C and greatly improve the performance of organic transistors in which the copper electrode is source/drain electrodes and QDTBDT2C is an active layer. The transistors display an electron mobility of 0.95 cm² V^-1 s^-1, to our knowledge, the highest electron mobility reported for copper electrode-based n-type transistors and nearly two times higher than that of the Au electrode-based devices. These results demonstrate the potential applications of Cu-QDTBDT2C complex in organic electronics, and the unique properties of QDTBDT2C (spontaneously reacting with copper) provide a new insight into the design of n-type organic semiconductors for copper electrode-based organic transistors.