Germanium-OLED short-wave infrared-to-visible upconverters

Infrared-to-visible upconverters consisting of infrared photodetectors (PDs) with visible light-emitting diodes (LEDs) to directly visualize infrared images without intermediate electronics have stimulated research interest. However, existing upconverters mostly detect infrared only in the near-infrared region, preventing the extensive short-wave infrared (SWIR) application. Here, we innovatively integrate strong-SWIR-response n-type germanium (Ge)/indium tin oxide (ITO) PDs with phosphorescence organic LEDs (OLEDs) to realize the efficient upconversion of SWIR to green light through a simple fabrication process. The ITO layers not only construct Schottky heterojunction with the Ge to improve SWIR detection ability but also provide the photogenerated carriers transport channel from PDs to OLEDs. As a result, the Ge-OLED upconverters exhibit the efficient upconversion of SWIR and high p–p efficiency of 7%.