Fabrication of an all-spin-coated CdSe/ZnS quantum dot light-emitting diode

Due to their unique technical properties, the importance of semiconductor nanocrystal quantum dots (QDs) increased over the last decades especially for the use of quantum dot light-emitting diodes (QD-LED) [1,2] or detectors [3]. In present QD-LED arrangements, layer stacks e.g. hole injection layer (HIL), hole transport layer (HTL), QD layer (QDL), hole blocking layer (HBL), and electron transport layer (ETL) are mostly formed by two or more process steps including spin-coating, thermal deposition or vapor deposition. The latter in general is used for assembling the ETL, because the QDs active matrix group (ligands) is unstable for organic solvents. Nevertheless a reduction of process steps and thus decreasing material consumption could be an advance in manufacturing QD-LEDs. Therefore we discuss the fabrication of an all-spin-coated CdSe/ZnS core shell type QD-LED only consisting of HIL, QDL, and ETL showing electroluminescence at 610 nm. Thereby the used ETL addition ally fulfils the function as HBL. Although the ETL has high electron mobility, the QD-LEDs conductivity was improved further through thermal annealing steps while fabrication.