Organic phototransistor based on intramolecular charge transfer in a bifunctional spiro compound

We report on the fabrication of organic phototransistors based on the spiro-conjugated molecule 2,7-bis-(N,N′-diphenylamino)-2′,7′-bis(biphenyl-4-yl)-9,9′-spirobifluorene. Intramolecular charge transfer leads to an increase in charge carrier density, providing the amplification effect. The sensitivity is better than 1 A/W for ultraviolet light at 370 nm, making the device interesting for sensor applications.