Keto defect sites in fluorene-based organic field-effect transistors: The origin of rapid degradation on the performance of the device

The effect of keto defects in fluorene units on the performance of organic field-effect transistors (OFETs) is examined on the basis of fluorene end-capped fused bithiophenes (BFTT) and biphenyl end-capped fused bithiophene oligomers(BPTT). A density of trap sites [N(sub t)] of around 2.7 x 10(super 15) cm(super -3) was found for the BPTT film due to the formation of keto defects after 6 h of UV irradiation.