High-performance all-solution-processed quantum dot near-infrared-to-visible upconversion devices for harvesting photogenerated electrons

All-solution-processed quantum dot (QD) upconversion devices were realized by constructing a colloidal PbS QD near-infrared (NIR ∼ 1 μm)-sensitive layer on the cathode side of a red CdSe quantum dot light-emitting diode (QLED). Different from conventional upconversion devices, we utilized the photogenerated electrons rather than the holes created in the NIR-sensitive layer to inject into the QLED for visible light emission. Consequently, we obtained high-performance devices with a maximum photon-to-photon conversion efficiency of 3.35% and a luminance on-off ratio of approximately 8 × 103. The results indicate that the device structure could be used to realize low-cost and portable high-performance QD-based upconversion devices via solution-processing.