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Trap engineering in solution processed PbSe quantum dots for high-speed mid-IR photodetectors

Abstract

The ongoing quest in finding methods to control the trap states in solution processed nanostructures (trap engineering) will revolutionise the applications of nanomaterials for optoelectronic purposes. In this paper, we present a new combined experimental/theoretical approach (molecular orbital theory) allowing a new view on trap engineering of nanostructures for applications in photodetectors. PbSe quantum dots (QDs) of about 20-50 nm diameter were prepared in a solution-based process from lead acetate (Pb(OAc)2), iodide (PbI2), and chloride (PbCl2), respectively. Comparison of the dangling acetate (OAc‒) versus the spherical monoatomic surface ligands chloride (Cl‒) and iodide (I‒) and varying the covalent/ionic character of the particle-surface ligand (ionic: OAc‒ > Cl‒ > I‒ : covalent) bond allowed interesting insight into what governs the trap states. Density functional theory (DFT) calculations are used to study band structures and density of states and show trap states localised within bandgap moving to conduction or valence band upon interaction of surface metal atoms with the surface ligands. Infrared detectors based on these materials are fabricated and allowed high-speed mid-infrared photo-detection with 100 ns rise and 110 ns fall response times.

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Publication details

The article was received on 03 Dec 2018, accepted on 15 Apr 2019 and first published on 15 Apr 2019


Article type: Paper
DOI: 10.1039/C8TC06093B
Citation: J. Mater. Chem. C, 2019, Accepted Manuscript

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    Trap engineering in solution processed PbSe quantum dots for high-speed mid-IR photodetectors

    A. Klein, M. Dolatyari, A. Rostami and S. Mathur, J. Mater. Chem. C, 2019, Accepted Manuscript , DOI: 10.1039/C8TC06093B

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