Stability of Quantum-Dot Light Emitting Diodes with Alkali Metal Carbonates Blending in Mg Doped ZnO Electron Transport Layer.

We report here the fabrication of highly efficient and long-lasting quantum-dot light emitting diodes (QLEDs) by blending various alkali metal carbonate in magnesium (Mg) doped zinc oxide (ZnO) (MZO) electron transport layer (ETL). Alkali metal carbonates blending in MZO, XCO:MZO, control the band-gap, electrical properties, and thermal stability. This can therefore enhance the operational lifetime of QLEDs. It is found that the conductivity of XCO:MZO film can be controlled and the thermal stability of ETLs could be improved by XCO blending in MZO. The inverted red QLEDs (R-QLEDs) with CsCO:MZO, RbCO:MZO, and KCO:MZO ETLs exhibited the operational lifetime of 407 h for the R-QLEDs with CsCO:MZO, 620 h with RbCO:MZO and 94 h with KCO:MZO ETLs at T with the initial luminance of 1000 cd/m. Note that all red QLEDs showed the high brightness over 150,000 cd/m. But the R-QLEDs with NaCO:MZO and LiCO:MZO ETLs exhibited shorter operational lifetime and poor brightness than the R-QLED with pristine MZO ETL.