Highly Luminescent Blue-Emitting In1-xGaxP@ZnS Quantum Dots and their Application in QLEDs with Inverted Structure

In order to resolve the issues of uncontrollably high reactivity of tris(trimethylsilyl)phosphine, widely used P precursor and very low solubility of metal halide precursors in non-coordinating solvent with ligands in the synthesis of environmentally benign III-V quantum dots, we created bis(trimethylsilyl)phosphine, HP(TMS)2, new P precursor with controllable reactivity and new metal complex precursors (Indium-trioctylphosphine, In-TOP; Ga-TOP; Zn-TOP) soluble in octadecene, non-coordinating solvent with dodecanethiol, C12SH. Another challenging issue with III-V quantum dots is to generate highly luminescent photostable blue-emitting nanaocrystals. We present the way of synthesizing pure III-V In1-xGaxP blue-emitting alloy core in non-coordination solvent. Gallium is introduced in the core to adjust the exciton energy effectively and to lessen lattice mismatch with zinc sulfide shell which contributes to the removal of surface defects and the enhancement of the photostability, and thus enhancing the photoluminescent quantum yield (PLQY) and the high color purity of quantum dots with narrow full width at half maximum (FWHM). The blue-emitting quantum dots, In1-xGaxP@ZnS of outstanding quality (PLQY = 65 %, FWHM = 46 nm) is successfully synthesized with our new P and metal complex precursors. Furthermore, we apply those QDs to fabricate In-Ga-based blue-emitting quantum dot light-emitting devices (QLEDs) with the external quantum efficiency of 0.20 % which is the best among the III-V-based blue-emitting QLEDs reported so far.