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

Hyo-Min Kim; Wonkyeong Jeong; Joo Hyun Kim; Jin Jang

doi:10.3390/nano10122423

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

Nanomaterials (Basel). 2020 Dec 4;10(12):2423. doi: 10.3390/nano10122423.

Authors

Hyo-Min Kim¹, Wonkyeong Jeong¹, Joo Hyun Kim¹, Jin Jang¹

Affiliation

¹ Department of Information Display and Advanced Display Research Center, Kyung Hee University, 26 Kyungheedae-ro, Dongdaemun-gu, Seoul 02447, Korea.

Abstract

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, X₂CO₃: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 X₂CO₃:MZO film can be controlled and the thermal stability of ETLs could be improved by X₂CO₃ blending in MZO. The inverted red QLEDs (R-QLEDs) with Cs₂CO₃:MZO, Rb₂CO₃:MZO, and K₂CO₃:MZO ETLs exhibited the operational lifetime of 407 h for the R-QLEDs with Cs₂CO₃:MZO, 620 h with Rb₂CO₃:MZO and 94 h with K₂CO₃:MZO ETLs at T₉₅ with the initial luminance of 1000 cd/m². Note that all red QLEDs showed the high brightness over 150,000 cd/m². But the R-QLEDs with Na₂CO₃:MZO and Li₂CO₃:MZO ETLs exhibited shorter operational lifetime and poor brightness than the R-QLED with pristine MZO ETL.

Keywords: Mg doped ZnO; QLED; alkali metal carbonate; metal oxide; operational lifetime.