Light responsive amorphous organic field-effect transistor based on spiro-linked compound

Light responsive organic field-effect transistors based on spiro-linked compound 2,7-bis-(N,N′-diphenylamino)-2′,7′-bis(spirobifluorene-2-yl)-9,9′-spirobifluorene is reported. The mechanism of light responsive transistor operation is based on intramolecular charge transfer between two molecular halves, which leads to an increase in charge carrier density upon illumination with ultraviolet light, thus providing the amplification effect. A ratio of photocurrent to dark current of up to 2.1 × 103 can be obtained. The drain current in the accumulation regime remains relatively unaffected by the illumination. However, the illumination strongly shifts the threshold voltage as far as 50 V, but does not change the field-effect mobility of the charge carriers.