Near-infrared absorbing cyanine dyes for all-organic optical upconversion devices.

The development of near-infrared (NIR) photodetection technologies is driven by emerging applications such as medical imaging or optical sensors for electronic displays and machine vision. An all-organic upconverter (OUD) is a device that converts incident NIR light directly into visible light and consists of a monolithic stack of a NIR organic photodetector (OPD) and a visible organic light-emitting diode (OLED). We present OUDs that consist of NIR heptamethine cyanine dyes/C 60 fullerene OPDs and a fluorescent tris(8-hydroxyquinolinato)aluminium (Alq 3) OLED. The device metrics of performance are a high external quantum efficiency (EQE) of 43% of the OPD part and an OUD luminance turn-on at low bias voltages of 2 V. The dynamic response of the photocurrent and luminance is linear over a NIR light range corresponding to 26 dB. These OUDs upconvert NIR light at 830 nm to green light with a photon-to-photon conversion efficiency of 0.61%, close to the expected maximum. Image 1 • Two cyanines were used as NIR sensitive layers in organic upconversion devices. • Devices successfully upconverted NIR light at 830 nm to visible light. • Upconverters had a low turn on voltage (2 V) and linear response to NIR light (26 dB). • The luminance on/off ratio was 4200 at 5 V • A photon to photon conversion efficiency of 0,61% was achieved. [ABSTRACT FROM AUTHOR]