Size-Dependent Optical Properties of InP Colloidal Quantum Dots

Abstract

Indium phosphide colloidal quantum dots (CQDs) are the main alternative for toxic and restricted Cd based CQDs for lighting and display applications. Here we systematically report on the size-dependent optical absorption, ensemble, and single particle photoluminescence (PL) and biexciton lifetimes of core-only InP CQDs. This systematic study is enabled by improvements in the synthesis of InP CQDs to yield a broad size series of monodisperse core-only InP CQDs with narrow absorption and PL line width and significant PL quantum yield.

Near-Unity Photoluminescence Quantum Yield of Core-Only InP Quantum Dots via a Simple Postsynthetic InF3 Treatment

“… 45 The synthesis is performed under an atmosphere of Ar/H 2 to further minimize the oxidation of the surface of the InP QDs. 46 , 47 We find that the degree of surface oxidation is indeed minimized by using this gas mixture and by using a heat-up synthesis versus a hot-injection synthesis. A one pulse 31 P ssNMR spectrum of the InP QDs after synthesis is shown in Figure 1 A in black.…”

The Narrow Synthetic Window for Highly Homogenous InP Quantum Dots toward Narrow Red Emission

“…According to the LaMer model, higher reactive precursor leads to smaller size QDs that exhibit shorter absorption wavelengths because of quantum confinement effect . The large size and heterogeneous size distribution of InP seeds synthesized without TOP can be inferred from the flat absorption spectra at around 600 nm (Figure S7).…”

“…According to the LaMer model, 41 higher reactive precursor leads to smaller size QDs that exhibit shorter absorption wavelengths because of quantum confinement effect. 42 The large size and heterogeneous size distribution of InP seeds synthesized without TOP can be inferred from the flat absorption spectra at around 600 nm (Figure S7). The formation of In-oleate−TOP complexes may reduce the bonding between In 3+ and oleic acid and then elevate the reactivity of indium precursor and lead to the generation of small InP seeds.…”

Surface-Originated Weak Confinement in Tetrahedral Indium Arsenide Quantum Dots

“…Clearly, the sizing curve of tetrahedral InAs QDs is in lower E g when compared to that of spherical shapes reported in previous literature. ,,− This implies unconventionally weaker confinement of the tetrahedron. At first glance, this might appear to contradict the common notion that tetrahedrons should have higher confinement energy according to the particle-in-a-box (PIB) model. , Considering that the opposite trend is evident in InP QDs despite sharing the same tetrahedral geometry (Figure S12), ,, our observation in InAs QDs raises questions regarding potential additional factors influencing the electronic structure in the QC regime. We find that factors such as ligand type, surface-dependent electron effective mass, and exciton binding energy cannot fully offer valid explanations (Supporting Information Discussion 3).…”