Integrated tandem device with photoactive layer for near-infrared to visible upconversion imaging.

An efficient organic near-infrared (NIR) to visible upconversion imaging device is obtained by integrating a photoactive buffer layer between two organic light-emitting diodes in a tandem configuration. As both types of photo-carriers (electrons and holes) are harvested to generate visible photons, this tandem device exhibits a significantly higher On/Off switching and has higher photon-photon conversion efficiency than conventional upconversion devices. We show that a high 5% photon-photon conversion rate is possible by optimizing the various functional layers in the tandem structure. We also demonstrate that a pixel-less NIR imaging chip can be made simply by using a large area single tandem organic upconversion device. [ABSTRACT FROM AUTHOR]