Organic photodetector with built-in amplification for the detection of visible light with low optical power

We report on an organic-based photodetector that integrates a dual-gate organic thin-film transistor (DG-OTFT) with an organic photodiode (OPD) to produce a device with a high effective responsivity at low optical power and video-rate compatible response. In this device, the OPD operates in photovoltaic mode, instead of the commonly used photoconductive mode, to modulate one of the gate voltages of the DG-OTFT. Effective responsivity values of 10 A W−1 are measured at optical power values lower than 10 nW at 635 nm. Modeling of the operation of this new photodetector suggests that effective responsivity values up to 105 A W−1 can be achieved at optical powers of 1 nW using current printing technology and state-of-the-art organic semiconductors.