Dependence of the Photoluminescence of Hydrophilic CuInS2 Colloidal Quantum Dots on Cu-to-In Molar Ratios
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Copper indium sulfide (CIS) quantum dots (QDs) are attractive as potential optoelectronic devices, since they have large absorption coefficients across a broad spectral range, size- and composition-tunable photoluminescence from the visible to the near-infrared, and low toxicity. However, CIS QDs should be hydrophilic in certain applications. In this present work, hydrophilic CIS and CIS/ZnS colloidal QDs were synthesized by a one-pot environmentally-friendly route employing N,N-dimethylformamide (DMF) as the solvent and in situ generated H2S as the sulphur precursor. The effect of stoichiometry was investigated by varying the feeding molar ratios of Cu/In, which did not affect the crystalline structure of the CIS colloidal QDs, while the optical property was influenced significantly. With the decrease of the feeding molar ratios of Cu/In, the band gap of the resulting CIS colloidal QDs had blue-shifts and relative photoluminescence quantum yield of the corresponding CIS/ZnS colloidal QDs increased monotonically.
KeywordsHydrophilic CuInS2 and CuInS2/ZnS quantum dots Cu-to-In ratios optical stability
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Financial support from National Natural Science Foundation of China (No. 51302096), China Scholarship Council (Grant Nos. 201806160042 and 201806160191), the Fundamental Research Funds for the Central Universities (Grant Nos. 2017KFYXJJ039 and 2015TS051), the Hubei Provincial Natural Science Foundation of China (Grant No. ZRMS2017000370), the Fundamental Research Funds of Wuhan City (No. 2016060101010075), and the Innovation Foundation of the Shenzhen Government (JCYJ20160429182959405) are acknowledged. The authors thank the Analytical and Testing Center of Huazhong University of Science and Technology and Maryland NanoCenter for making available the shared experimental facilities.
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