Electroluminescence of 2,4-bis(4- (2′ -thiophene-yl)phenyl)thiophene in organic light-emitting field-effect transistors

We succeeded in observing electroluminescence (EL) of 2,4-bis(4- (2′ -thiophene-yl)phenyl)thio-phene (TPTPT) as an active layer in an organic field-effect transistor (OFET). In particular, an OFET with a short channel of dSD=0.8 μm demonstrated higher EL efficiency than one with a much longer channel (dSD =9.8 μm). We observed a maximum EL quantum efficiency (η_max) of 6.4×10-3 % in the short-channel-length device at an applied source-drain voltage of Vd=-100 V and a gate voltage of Vg=-40 V. From the OFET characteristics, although the TPTPT layer demonstrated typical p -type operation, the occurrence of EL clearly indicated simultaneous hole and electron injection from the source and drain electronics, respectively, under high Vd and Vg.