Abstract
Colloidal quantum dots light-emitting diodes (QD-LEDs) have been investigated for several decades. Compared with their green and red counterparts, the hole injection is more difficult for blue QDs due to their large optical band gap and relatively low highest occupied molecular orbital level. High-performance blue QD-LEDs are demonstrated by inserting a thin deoxyribonucleic acid (DNA) buffer layer between hole transport layer and ZnCdS/ZnS core/shell QDs layer. This DNA buffer layer can effectively enhance the hole injection efficiency, meanwhile its high lowest unoccupied molecular orbital level can help the injected electrons to be confined in the emitting layer, thus ensuring the charge balance in the QDs layer and an excellent recombination efficiency. After utilizing DNA as buffer layer, the maximum luminance is significantly increased from 10 218 to 16 655 cd m(-2) and the external quantum efficiency is increased from 4.39% to 5.65%. These devices provide a saturated blue emission with emission peak located at 462 nm and full width at half maximum of 21 nm. This saturated blue emission makes it suitable for commercial applications. The results indicate that DNA is a promising material for regulating charge balance in the emitting layer for manufacturing high performance QD-LEDs.