Organic Photodiodes with an Extended Responsivity Using Ultrastrong Light–Matter Coupling

In organic photodiodes (OPDs), light is absorbed by excitons that dissociate to generate photocurrent. Here, we demonstrate a novel type of OPD in which light is absorbed by polaritons, hybrid light–matter states. We demonstrate polariton OPDs operating in the ultrastrong coupling regime at visible and infrared wavelengths. These devices can be engineered to show narrow responsivity with a very weak angle-dependence. More importantly, they can be tuned to operate in a spectral range outside that of the bare exciton absorption. Remarkably, we show that the responsivity of a polariton OPD can be pushed to near-infrared wavelengths, where few organic absorbers are available, with external quantum efficiencies exceeding those of our control OPD.