Electrical characterization of thieno[3,4-b]thiophene and benzodithiophene copolymer using field-effect transistor configuration

摘要

A thieno[3,4-b]thiophene and benzodithiophene copolymer PTB7, which has received much attention as a donor material of organic solar cells, is electrically characterized using a field-effect transistor (FET) configuration. The hole mobility of PTB7 FETs is ～2.0 × 10~(-3)cm~2·V~(-1)·s~(-1), which is independent of annealing temperature, while the threshold voltage shifts towards a negative value with increasing annealing temperature. This is due to the increase in the density of deep trapping states with thermal annealing. The threshold voltage also shifts towards a negative value after aging, indicating that additional deep trapping states are generated in PTB7 thin films even at room temperature.