Transparent organic upconversion device targeting high- grade infrared visual image

Infrared-to-visible transparent upconverter offers an appealing prospect of demonstrating in situ invisible information without interfering with the intrinsic vision of human eyes. However, previous studies required high operational voltage for visible light emission failing to meet the prerequisite of practical application. Here, we report an organic upconversion device composed of a single photoactive material ClAlPc for sensing infrared light and subsequent visualization by BCzPh:CN-T2T exciplex co-hosted phosphorescent light-emitting diode. Incident NIR signal (λmax at 780 nm) is upconverted into visible light emission (λmax at 523 nm) under an onset bias voltage of merely 1.7 V by the virtue of barrier-less bipolar exciplex design. Particularly, the device exhibits linear dynamic luminance toward NIR power density down to 34 μW/cm2 and real-time response to frequency-modulated NIR signal up to 10 kHz. By comprising a transparent multilayered electrode for see-through upconverter, a high-quality infrared visual image with a maximum resolution of 1588 dpi is demonstrated.