Electron transport phenomena at the interface of Al electrode and heavily doped degenerate ZnO nanoparticles in quantum dot light emitting diode
- Electron transport phenomena at the interface of Al electrode and heavily doped degenerate ZnO nanoparticles in quantum dot light emitting diode
- 최원국; 이연주; 김정혁; 김홍희; 이윤재; 최헌진
- ZnO nanoparticles; electron transport layer; Quantum dots; LIght-emitting diodes; degenerate semiconductor; oxygen vacancy
- Issue Date
- VOL 30, NO 3-035207-9
- ZnO nanoparticles (NPs) of 4– 5 nm, widely adopted as an electron transport layer (ETL) in quantum dot light emitting diodes (QD-LEDs), were synthesized using the solution-precipitation process. It is notable that synthesized ZnO NPs are highly degenerate intrinsic semiconductors and their donor concentration can be increased up to N D = 6.9 × 1021 cm– 3 by annealing at 140 °C in air. An optical bandgap increase of as large as 0.16– 0.33 eV by degeneracy is explained well by the Burstein– Moss shift. In order to investigate the influence of intrinsic defects of ZnO NP ETLs on the performance of QD-LED devices without a combined annealing temperature between ZnO NP ETLs and the emissive QD layer, pre-annealed ZnO NPs at 60 °C, 90 °C, 140 °C, and 180 °C were spin-coated on the annealed QD layer without further post-annealing. As the annealing temperature increases from 60 °C to 180 °C, the defect density related to oxygen vacancy (V O) in ZnO NPs is reduced from 34.4% to 17.8%, whereas the defect density of interstitial Zn (Zni) is increased. Increased Zni reduces the width (W) of the depletion region from 0.21 to 0.12 nm and lowers the Schottky barrier (ФB) between ZnO NPs and the Al electrode from 1.19 to 0.98 eV. We reveal for the first time that carrier conduction between ZnO NP ETLs and the Al electrode is largely affected by the concentration of Zni above the conduction band minimum, and effectively described by space charge limited current and trap charge limited current models.
- Appears in Collections:
- KIST Publication > Article
- Files in This Item:
There are no files associated with this item.
- RIS (EndNote)
- XLS (Excel)
Items in DSpace are protected by copyright, with all rights reserved, unless otherwise indicated.