Deep-red and near-infrared light-emitting electrochemical cells employing perovskite color conversion layers with EQE >10%

Solid-state light-emitting electrochemical cells (LECs) exhibit high potential for application in consumer electronics due to their promising advantages of solution-processable simple device architecture, low-voltage operation, and compatibility with inert metal electrodes. However, low device efficiencies of deep-red and near-infrared (NIR) LECs hinder their application since long-wavelength organic emissive materials commonly suffer from moderate emission efficiencies. To improve the device efficiencies of deep-red and NIR LECs, combinational devices by integrating efficient blue-green LECs employing an ionic transition metal complex with perovskite color conversion layers are demonstrated. Saturated deep-red and NIR output emission can be generated through energy down-conversion. Furthermore, the light extraction enhancement technique based on a diffusive layer beneath the indium-tin oxide layer is utilized to boost the device efficiency. Both the optical simulation and experiments confirm doubled light output via the aid of such a diffusive layer. These combinational devices deliver saturated output emission peaks at 640, 672, and 700 nm with a narrow full width at half maximum 10%. These device efficiencies are among the highest reported values for deep-red and NIR LECs. This work shows an alternative way to overcome the limitation of low emission efficiencies for long-wavelength organic emissive materials and thus successfully realizes efficient deep-red and NIR LECs.

Automated summary

This research demonstrates the enhancement of device efficiencies for deep-red and NIR LECs by integrating efficient blue-green LECs with perovskite color conversion layers. The use of light extraction enhancement technique and diffusive layer further improves the device efficiency. The combinational devices achieve high device efficiencies in the deep-red and NIR wavelength range.