Synthesis and photovoltaic properties of a low-band-gap copolymer of dithieno[3,2- b:2′,3′-d]thiophene and dithienylquinoxaline

The synthesis and photovoltaic properties of new thiophene-bridged dithienothiophene (DTT)-containing D-π-A conjugated low-band-gap and solution-processable polymers was reported. The low-band-gap copolymer of Dithieno[3,2-b:2',3'-d]thiophene and Dithienylquinoxaline was considered. The absorption spectra of PTDTTTQX were taken in chlorobenzene (CB) and in o-dichlorobenzene (ODCB) solution. A study of drain current versus drain-source voltage characteristics and transfer characteristics of the organic thin film transistors (OTFT) based on PTDTTTQX shows good saturation behavior with clear saturation currents. A study of the external quantum efficiency (EQE) of the device shows efficient photoconversion efficiency from 400 to 700 nm, which covers most of the visible wavelength range. The shape of the EQE plot is similar to the absorption spectrum of the device, indicating that all absorption wavelengths of the polymer contribute to photocurrent generation.