Hybrid image sensor of small molecule organic photodiode on CMOS - Integration and characterization

Organic photodiodes (OPDs) for its interesting optoelectronic properties has the potential to be utilized with complementary metal-oxide-semiconductor (CMOS) circuit for imaging, automotive, and security based applications. To achieve such a hybrid device as an image sensor, it is imperative that the quality of the OPD remains high on the CMOS substrate and that it has a well-connected optoelectronic interface with the underneath readout integrated circuit (ROIC) for efficient photogeneration and signal readout. Here, we demonstrate seamless integration of a thermally deposited visible light sensitive small molecule OPD on a standard commercial CMOS substrate using optimized doped PCBM buffer layer. Under a standard power supply voltage of 3 V, this hybrid device shows an excellent photolinearity in the entire bias regime, a high pixel sensitivity of 2 V/Lux.sec, a dynamic range (DR) of 71 dB, and a low dark leakage current density of 1 nA/cm². Moreover, the integrated OPD has a minimum bandwidth of 400 kHz. The photoresponse nonuniformity being only 1.7%, achieved under research lab conditions, strengthens the notion that this fully-CMOS compatible technology has the potential to be applied in high-performance large-scale imaging array.