Control of the Reaction Kinetics of Monodispersed InP/ZnSeS_/ZnS-Based Quantum Dots Using Organophosphorus Compounds for Electroluminescent Devices

Abstract

Green emissive InP-based quantum dots (QDs) remain less developed than red QDs because of the difficulty of controlling the reactivity of small InP cores. Herein, we report the synthesis of monodispersed green InP-based QDs using tris(dimethylamino)phosphine, a considerably inexpensive and safer phosphorus source compared to conventional tris(trimethylsilyl)phosphine. An organophosphorus compound, trioctylphosphine, was used to control the reaction kinetics by slowing the progression of the nucleation process, which weakened the aggregation behavior of the clusters and improved the size distribution. The synthesized green emissive InP/ZnSeS/ZnS QDs exhibited a photoluminescence (PL) peak at 515 nm with an enhancement of the full width at half-maximum from 66 to 46 nm and the PL quantum yield from 61% to 70%. An electroluminescent device was fabricated, and the electron transport layer was optimized by changing the layer thickness. The optimized device structure improved the charge balance and increased the external quantum efficiency from 2.1% to 3.5%.

Tuning the Shades of Red Emission in InP/ZnSe/ZnS Nanocrystals with Narrow Full Width for Fabrication of Light-Emitting Diodes

“…In Figure C, the XRD pattern indicates that the samples have been crystallized in a zinc blend cubic structure with the lattice plane Miller indices (111), (220), and (311). Considering the XRD patterns of the InP (JCPDS 32-0452), ZnSe (JCPDS 80-0021), and ZnS (JCPDS 80-0020) bulk structures that are indicated at the bottom of Figure C, the reflection peaks of the prepared QDs are between peaks related to ZnSe and ZnS . The pattern is closer to that of ZnSe due to the thick ZnSe layer coated around the InP QDs.…”

“…Considering the XRD patterns of the InP (JCPDS 32-0452), ZnSe (JCPDS 80-0021), and ZnS (JCPDS 80-0020) bulk structures that are indicated at the bottom of Figure 1 C, the reflection peaks of the prepared QDs are between peaks related to ZnSe and ZnS. 28 The pattern is closer to that of ZnSe due to the thick ZnSe layer coated around the InP QDs. To evaluate the morphology of the purified QDs, a STEM image was captured, which indicates the formation of tiny, three-dimensionally confined NCs with an average size of about 11.05 nm.…”