Tunable structural and optical properties of CuInS2 colloidal quantum dots as photovoltaic absorbers

Ming, Shanna-Kay; A. Taylor, Richard; D. McNaughter, Paul; J. Lewis, David; A. Leontiadou, Marina; O'Brien, Paul

Abstract

Facile phase selective synthesis of CuInS2 (CIS) nanostructures has been an important pursuit because of the opportunity for tunable optical properties of the phases, and in this respect is investigated by hot-injection colloidal synthesis in this study. Relatively monodispersed colloidal quantum dots (3.8–5.6 nm) of predominantly chalcopyrite structure synthesized at 140, 180 and 210 °C over 60 minutes from copper(II) hexafluoroacetylacetonate hydrate and indium(III) diethyldithiocarbamate precursors exhibit temperature-dependent structural variability. The slightly off-stoichiometric quantum dots are copper-deficient in which copper vacancies Image ID:d1ra03659a-t1.gif, indium interstitials Image ID:d1ra03659a-t2.gif, indium–copper anti-sites Image ID:d1ra03659a-t3.gif and surface trapping states are likely implicated in broad photoluminescence emission with short radiative lifetimes, τ1, τ2, and τ3 of 1.5–2.1, 7.8–13.9 and 55.2–70.8 ns and particle-size dependent tunable band gaps between 2.25 and 2.32 eV. Further structural and optical tunability (Eg between 2.03 and 2.28 eV) is achieved with possible time-dependent wurtzite to chalcopyrite phase transformation at 180 °C likely involving a dynamic interplay of kinetic and thermodynamic factors.

• Journal Article Type: Article
• Acceptance Date: Jun 9, 2021
• Publication Date: 2021
• Deposit Date: Jul 18, 2025
• Publicly Available Date: Jul 21, 2025
• Journal: RSC Advances
• Print ISSN: 2046-2069
• Publisher: Royal Society of Chemistry
• Peer Reviewed: Peer Reviewed
• Issue: 35
• DOI: https://doi.org/10.1039/D1RA03659A