Multispectral Organic Photodetectors and Applications

Spectral response of organic photodetectors (OPDs) is determined by the absorption of the active materials and optical profile in the devices. Single-band OPDs optimized for photodetection at specific spectral ranges have been reported. However, the reports on OPDs for multispectral detection are rather rare. It is a great challenge to achieve high-performance multispectral OPDs. This talk discusses a novel filter-free multispectral OPD comprising a back-to-back stacked double bulk heterojunction (BHJ) structure. The front BHJ responds to short-wavelength light, e.g., visible, whereas the rear BHJ responds to long-wavelength light, e.g., near-infrared electromagnetic waves. The back-to-back stacked double BHJ OPD allows multispectral detection that can be controlled by the polarity of a bias applied between the two contacts in the OPD. The double BHJ OPD also exhibits a broadband photoresponse when it is operated using a 50% duty-cycled square-wave supply voltage. The multispectral OPDs enable applications in areas such as health and security monitoring, artificial intelligence, high-resolution image sensing, Internet of Things, and optical communications.