28‐4: Positive Aging Resulted in Highly Efficient Blue Quantum Rod Light Emitting Diodes

Abstract

The synthesis of blue quantum rods (QRs) is challenging due to fast kinetics and a significant shift in color during the synthesis of w‐CdSe seeds. Herein, we synthesized highly bright CdSe/ZnxCd1‐xS/ZnS core/shell blue QRs with an emission wavelength of 480 nm and fabricated blue QRLEDs. We found that the aging process of the QRLEDs significantly improved their performance by slowly reacting Al with ZnMgO and forming an AlOx interlayer among the ZnMgO/Al, which increased electron injection by over 3x times. The AlOx layer minimized the electron injection barrier and produced highly conductive ZnMgO by forming oxidation deficiency. Additionally, the exciton quenching suppressed at the QRs/ZnMgO/Al interface, and film morphology also changed among the QRs/ZnMgO stacks with the time. As a result, the aged QRLEDs showed an EQE of 9.4% and luminance of 61500 cd/m2, which is 2.6x and 3x times higher than the freshly made QRLEDs. These are the highest reported numbers in EQE and luminance of blue QRLEDs. Additionally, the durability of the blue QRLEDs significantly improved from 50 to 300 hours at 100 cd/m2 initial luminance. Overall, the use of QRs in LEDs greatly improves device efficiency and brightness.