Extremely Low‐Threshold Amplified Spontaneous Emission of 9,9′‐Spirobifluorene Derivatives and Electroluminescence from Field‐Effect Transistor Structure

Abstract

Abstract By doping 2,7‐bis[4‐( N ‐carbazole)phenylvinyl]‐9,9′‐spirobifluorene (spiro‐SBCz) into a wide energy gap 4,4′‐bis(9‐carbazole)‐2,2′‐biphenyl (CBP) host, we demonstrate an extremely low ASE threshold of E th = (0.11 ± 0.05) μJ cm –2 (220 W cm –2 ) which is the lowest ASE threshold ever reported. In addition, we confirmed that the spiro‐SBCz thin film functions as an active light emitting layer in organic light‐emitting diode (OLED) and a field‐effect transistor (FET). In particular, we succeeded to obtain linear electroluminescence in the FET structure which will be useful for future organic laser diodes.