Dithienobenzothiadiazole-Based Conjugated Polymer: Processing Solvent-Relied Interchain Aggregation and Device Performances in Field-Effect Transistors and Polymer Solar Cells

摘要

DT f BT-Th _3, a new conjugated polymer based on dithienobenzothiadiazole and terthiophene, possesses a bandgap of ≈1.86 eV and a HOMO level of -5.27 eV. Due to strong interchain aggregation, DT f BT-Th _3 can not be well dissolved in chloro benzene (CB) and o -dichlorobenzene (DCB) at room temperature (RT), but the polymer can be processed from hot CB and DCB solutions of ≈100 °C. In CB, with a lower solvation ability, a certain polymer chain aggregation can be preserved, even in hot solution. DT f BT-Th 3 displays a fi eld-effect hole mobility of 0.55 cm ~2 V ~(-1) s ~(-1) when fabricated from hot CB solution, which is higher than that of the device processed from hot DCB (0.16 cm ~2 V ~(-1) s ~(-1)). In DT?BT-Th _3 -based polymer solar cells, a good power conversion effi ciency from 5.37% to 6.67% can be achieved with 150-300 nm thick active layers casted from hot CB solution, while the highest effi ciency for hot DCB-processed solar cells is only 5.07%. The results demonstrate that using a solvent with a lower solvation ability, as a "wet control" process, is benefi cial to preserve strong interchain aggregation of a conjugated polymer during solution processing, showing great potential to improve its performances in optoelectronic devices.