Abstract
Near infrared to visible up-conversion devices have every growing demand in a myriad of industrial sectors including photovoltaics, energy harvesting, medicine and imaging. Here we have demonstrated an up-conversion device which utilizes quantum dots for both infrared absorption and visible emission. The band structure of the device is designed and optimized with well-constructed carrier transport and blocking layers. The achieved up-conversion device exhibits an impressive conversion efficiency of over 6 %, with a high near infrared on-off ratio of over 10 4 . The device demonstrates a potential new approach for an up-conversion device designed solely on quantum dots with high efficiency.
Highlights
Near infrared (NIR) to visible up-conversion devices have attracted great attention due to their unique property of converting unobservable NIR light to visible light. This extension of human visual range brings some potential applications in biomedical, night vision and NIR imaging area [1]–[5]. Materials such as rare-earth doped crystals [6]–[8], organic materials rely on the triplet-triplet annihilation [9], [10] and quantum well nanostructures [11], [12] have shown their potential of achieving NIR to visible up-conversion based on two-photon absorption (TPA)
Semi-PD refers to semiconductor photodetector, QDPD refers to quantum dot photodetector and Pe-light emitting diode (LED) refers to perovskite LED
The P-P conversion efficiency could be further optimized by introducing phototransistors or surface roughness technologies
Summary
Near infrared (NIR) to visible up-conversion devices have attracted great attention due to their unique property of converting unobservable NIR light to visible light. Prototypical organic up-conversion devices were reported since 2002 [21], [22] by doping IR sensitive materials into carrier transport layer to achieve a carrier blocking property w/o IR This kind of method introduced inefficient carrier blocking and non-photogenerated carriers generally leading to poor luminance on-off ratio and low conversion efficiency. Sharp emission spectra of QDs-based LEDs have shown their potential of becoming the solution for the next-generation of display [37], [42] All these unique properties are extremely suitable for NIR-visible up-conversion devices. A high photon-to-photon conversion efficiency of 6.3 % is achieved when the device is working under a bias voltage of 15 V and a NIR source with power density of 14.1 uW/cm. The efficient solutionprocessed NIR-visible up-conversion device based on full QDs may eventually leads to high performance all-inorganic up-conversion devices
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