Synthesis of Deep Blue InP Quantum Dots via HF Etching for Light-Emitting Diodes
Wenda Zhang, Xijian Duan, Lei Chen, Kai Wang, Yujie Song, Weigao Wang, Xiao Wei Sun
Abstract
Red, green, and sky-blue InP quantum dots (QDs) are currently bridging the gap with CdSe-based QDs in terms of the photoluminescence quantum yields (PLQY). However, the sensitivity of InP QDs to water and oxygen, coupled with the increased specific surface area of smaller pure-blue and deep-blue QDs, leads to diminished PLQY, consequently restricting the fabrication of highly efficient blue InP quantum dot light-emitting diodes (QLEDs). Here, high-temperature nucleation is utilized to produce highly crystalline InP cores, followed by low-temperature HF etching. This dual-treatment method simultaneously addresses surface phosphate defects and diminishes QD size, ultimately yielding pure-blue InP QDs with a PLQY of 73% at 466 nm and deep-blue InP QDs with a PLQY of 52% at 451 nm. Notably, by fine-tuning the HF dosage, 421 nm deep-blue InP QDs, representing the shortest wavelength to date, were successfully prepared. Additionally, enhancing carrier injection efficiency was achieved by replacing long-chain 1-dodecanethiol (DDT) ligands with short-chain 1-octanethiol (OT) ligands through ligand exchange. QLEDs exhibited an external quantum efficiency of 0.8% with an emission wavelength of 468 nm, providing a perspective for the fabrication of InP blue QLEDs via this etching technique.