IR Sensor Based on Low Bandgap Organic Photodiode With Up-Converting Phosphor

We report an infrared (IR) sensor which is fabricated by integrating a PCPDTBT:PCBM organic photodiode (OPD) with an up-converting (UC) phosphor. The UC phosphor extends the response range by absorbing incoming light with a wavelength of 986 nm and re-emitting at 804 nm, which is a wavelength that can be absorbed by the active layer, resulting in a generation of a photocurrent. In order to ensure low reverse bias leakage current, PEDOT:PSS was not used as a hole transporting layer, which reduced reverse leakage current by two orders of magnitude compared with conventional hole transporting layers. An IR-emitting laser diode (with emission at 986 nm) is used as a light source to illuminate the sensor. The results demonstrate the proof of principle of sensing using polymer-based OPDs in the near-IR, with wider applications possible in areas, such as telecommunications or sensors if different UC phosphors are applied.