Luminescent Colloidal InSb Quantum Dots from In Situ Generated Single-Source Precursor

Abstract

Despite recent advances, the synthesis of colloidal InSb quantum dots (QDs) remains underdeveloped, mostly due to the lack of suitable precursors. In this work, we use Lewis acid–base interactions between Sb(III) and In(III) species formed at room temperature in situ from commercially available compounds ( viz. , InCl 3 , Sb[NMe 2 ] 3 and a primary alkylamine) to obtain InSb adduct complexes. These complexes are successfully used as precursors for the synthesis of colloidal InSb QDs ranging from 2.8 to 18.2 nm in diameter by fast coreduction at sufficiently high temperatures (≥230 °C). Our findings allow us to propose a formation mechanism for the QDs synthesized in our work, which is based on a nonclassical nucleation event, followed by aggregative growth. This yields ensembles with multimodal size distributions, which can be fractionated in subensembles with relatively narrow polydispersity by postsynthetic size fractionation. InSb QDs with diameters below 7.0 nm have the zinc blende crystal structure, while ensembles of larger QDs (≥10 nm) consist of a mixture of wurtzite and zinc blende QDs. The QDs exhibit photoluminescence with small Stokes shifts and short radiative lifetimes, implying that the emission is due to band-edge recombination and that the direct nature of the bandgap of bulk InSb is preserved in InSb QDs. Finally, we constructed a sizing curve correlating the peak position of the lowest energy absorption transition with the QD diameters, which shows that the band gap of colloidal InSb QDs increases with size reduction following a 1/ d dependence.

Acid–Base Mediated Ligand Exchange on Near-Infrared Absorbing, Indium-Based III–V Colloidal Quantum Dots

“…These approaches yield access to InAs QDs absorbing from 750 to 1450 nm − and hold promise for large scale QD production. Importantly, this new approach to form InAs QDs was inspired by initial studies on InP QD synthesis and has been extended to form InSb and III–V alloys such as In­(As,Sb). − …”

Rapid, facile synthesis of InSb twinning superlattice nanowires with a high-frequency photoconductivity response

“…[59][60][61][62] Additionally, we see a single weak shoulder at around 1400 nm that can be attributed to a small amount of wide distribution in diameter and length of InSb NWs. 42 Fig. 1c displays a low-magnication transmission electron microscopy (TEM) image of the as-synthesized InSb NWs, which further demonstrated the NWs are crystalline in high quality with twinned structures.…”

“… 59–62 Additionally, we see a single weak shoulder at around 1400 nm that can be attributed to a small amount of wide distribution in diameter and length of InSb NWs. 42 …”

“…[36][37][38][39] However, the growth of InSb twinning superlattice nanowires by the above-mentioned methods has proven to be very challenging primarily attributed to the small ionicity with low bonding tendency and the high energy barrier (8.2 meV per atom) for the ZB/WZ phase transition compared with other III-V compound semiconductor nanowires. 37,[40][41][42] Furthermore, the rather small growth temperature window during the VLS growth process limited by the low melting point of InSb at approximately 520 C and the high decomposition temperature for usual Sb precursors, 43 severely hinder the thermodynamic regulation of zinc-blende (ZB) and wurtzite (WZ) phase formed alternately in a periodic nucleation process to obtain the twinning superlattices structure. 44 In striking comparison to the energy-intensive and time-consuming vapor-phase growth approaches, solution-based route via solution-liquid-solid (SLS) mechanism can proceed at relatively low temperatures (<300 C) and provide semiconductor nanowires with easy growth processes and adaptability for large-scale fabrication of nanowire-based devices.…”

Anisotropic growth of ZnO nanoparticles driven by the structure of amine surfactants: the role of surface dynamics in nanocrystal growth

“…During the synthesis of nano-objects in solution, the surfactant is generally assumed to play different roles, and primarily can act as ligand for the molecular species present in solution. [26][27][28] The metal precursor may thus be modified after its introduction in the reaction media before the nucleation process. The surfactant is also seen as a blocking agent (or surface stabilizing agent) during the nanocrystal (NC) growth process.…”