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, X(2)CO(3):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 X(2)CO(3):MZO film can be controlled and the thermal stability of ETLs could be improved by X(2)CO(3) blending in MZO. The inverted red QLEDs (R-QLEDs) with Cs(2)CO(3):MZO, Rb(2)CO(3):MZO, and K(2)CO(3):MZO ETLs exhibited the operational lifetime of 407 h for the R-QLEDs with Cs(2)CO(3):MZO, 620 h with Rb(2)CO(3):MZO and 94 h with K(2)CO(3):MZO ETLs at T(95) with the initial luminance of 1000 cd/m(2). Note that all red QLEDs showed the high brightness over 150,000 cd/m(2). But the R-QLEDs with Na(2)CO(3):MZO and Li(2)CO(3):MZO ETLs exhibited shorter operational lifetime and poor brightness than the R-QLED with pristine MZO ETL.