Lee, Yeon Ju Kim, Hong Hee Lee, Yun Jae Kim, Jung Hyuk Choi, Heon-Jin Choi, Won Kook 2024-01-19T21:02:00Z 2024-01-19T21:02:00Z 2021-09-02 2019-01 0957-4484 https://pubs.kist.re.kr/handle/201004/120458 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 x 10(21) cm(-3) by annealing at 140 degrees 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 degrees C, 90 degrees C, 140 degrees C, and 180 degrees C were spin-coated on the annealed QD layer without further post-annealing. As the annealing temperature increases from 60 degrees C to 180 degrees 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 (Zn-i ) is increased. Increased Zn-i reduces the width (W) of the depletion region from 0.21 to 0.12 nm and lowers the Schottky barrier (Phi(B)) 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 Zn-i above the conduction band minimum, and effectively described by space charge limited current and trap charge limited current models. English Institute of Physics Publishing Electron transport phenomena at the interface of Al electrode and heavily doped degenerate ZnO nanoparticles in quantum dot light emitting diode Article 10.1088/1361-6528/aaed98 1 Nanotechnology, v.30, no.3 Nanotechnology 30 3 N scie scopus 000450635000001 2-s2.0-85056721362 Nanoscience & Nanotechnology Materials Science, Multidisciplinary Physics, Applied Science & Technology - Other Topics Materials Science Physics Article FULL-COLOR PERFORMANCE EFFICIENT DEVICES DEFECTS DRIVEN GROWTH GREEN heavily doped intrinsic defects degenerate ZnO nanoparticles electron transport layer quantum dot light emitting diodes carrier conduction