Evolution from unimolecular to colloidal-quantum-dot-like character in chlorine or zinc incorporated InP magic size clusters

Yongju Kwon,Sungjee Kim,Dongho Kim,Anastasia Agnes,Sang Hyeon Lee,Juwon Oh,Eunjae Lee,Gyuhyun Bang,Jeongmin Kim

doi:10.1038/s41467-020-16855-9

Abstract

Magic-sized clusters (MSCs) can be isolated as intermediates in quantum dot (QD) synthesis, and they provide pivotal clues in understanding QD growth mechanisms. We report syntheses for two families of heterogeneous-atom-incorporated InP MSCs that have chlorine or zinc atoms. All the MSCs could be directly synthesized from conventional molecular precursors. Alternatively, each series of MSCs could be prepared by sequential conversions. 386-InP MSCs could be converted to F360-InP:Cl MSCs, then to F399-InP:Cl MSCs. Similarly, F360-InP:Zn MSCs could be converted to F408-InP:Zn MSCs, then to F393-InP:Zn MSCs. As the conversion proceeded, evolution from uni-molecule-like to QD-like characters was observed. Early stage MSCs showed active inter-state conversions in the excited states, which is characteristics of small molecules. Later stage MSCs exhibited narrow photoinduced absorptions at lower-energy region like QDs. The crystal structure also gradually evolved from polytwistane to more zinc-blende.

Highlights

Magic-sized clusters (MSCs) can be isolated as intermediates in quantum dot (QD) synthesis, and they provide pivotal clues in understanding quantum dots (QDs) growth mechanisms
We explored whether F360-incorporates chlorine (Cl) atoms (InP):Cl MSCs that had been prepared by conversion from 386-MA InP MSCs could be further converted to another species
Each series of MSCs could be prepared by sequential conversions. 386-InP MSCs could be converted to F360-InP:Cl MSCs, to F399-InP:Cl MSCs

Summary

Introduction

Magic-sized clusters (MSCs) can be isolated as intermediates in quantum dot (QD) synthesis, and they provide pivotal clues in understanding QD growth mechanisms. To rationally design high-quality InP QDs in molecular precision, the growth mechanisms from molecular precursors to QDs must be better understood. In this regard, there have been intensive studies, which revealed that InP QDs appear to be quite disparate from Cd-chalcogenide QDs in their growth mechanism[6,7,8]. Cossairt and co-workers published a seminal paper reporting synthesis of an InP MSC from molecular precursors of indium acetate (In(Ac)3), myristic acid (HMA), and tris(trimethylsilyl)phosphine ((TMS)3P), which exhibits the dominant absorption peak at 386 nm (denoted as 386-MA InP MSC)[6].

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Results

Conclusion