Cation co-doping into ZnS quantum dots: towards visible light sensing applications
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Bull Mater Sci (2020)43:301 https://doi.org/10.1007/s12034-020-02233-0
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Cation co-doping into ZnS quantum dots: towards visible light sensing applications G KRISHNAMURTHY GRANDHI1, MAHESH KRISHNA2, PAYEL MONDAL1,3 and RANJANI VISWANATHA1,2,3,* 1
New Chemistry Unit, Jawaharlal Nehru Centre for Advanced Scientific Research, Bangalore 560064, India International Centre for Materials Science, Jawaharlal Nehru Centre for Advanced Scientific Research, Bangalore 560064, India 3 School of Advanced Materials, Jawaharlal Nehru Centre for Advanced Scientific Research, Bangalore 560064, India *Author for correspondence ([email protected]) 2
MS received 2 January 2020; accepted 9 April 2020 Abstract. Efficient and environmentally benign visible light responsive materials have been sought after owing to their interesting applications such as visible light photocatalysis, visible light water splitting and visible light sensing. In this research study, the effect of co-doping on the absorption and electrical properties of ZnS quantum dots is studied. Upon co-doping of Fe and Cu into ZnS quantum dots, a new absorption band in the visible region is observed. Furthermore, these quantum dots show photoresponse in the visible region unlike their undoped counterparts that is only effective in the UV region, suggesting their utility in light sensing applications. Keywords.
1.
ZnS quantum dots; co-doping; non-toxic; visible light detection.
Introduction
Inorganic semiconducting materials that absorb visible light are of great interest for various applications such as photocatalysis [1,2], solar cells [3,4] and photodetectors [5]. Photodetectors with UV–visible–NIR spectral response have gained great attention due to their various applications in image sensing, communication and environmental monitoring [6,7]. Crystalline Si is one of the most studied systems that has been used for visible light detection [8]. However, its limitations like its weak absorption over the entire spectrum have limited its use in photodetectors. Oxide semiconductors have been found to be good candidates to replace Si in many electrical devices [9]. However, oxide semiconductor-based devices are transparent due to their very high band gap and hence limited to UV light detection [10]. Efforts have been made to improve the visible light response of these oxide semiconductors to some extent with the help of a polymer material as the lightabsorbing layer [11]. They were also used by blending with semiconductor quantum dots (QDs) [12]. For example, p-type doping in NiO results in visible light sensing [5]. Other than these oxide materials, there are extensive reports on the UV-based photodetectors which are based on high band gap materials such as TiO2, ZnO and ZnS This article is part of the Topical Collection: SAMat Focus Issue.
nanostructures [13–15]. Semiconductor materials like CdS [16], ZnTe [17] and In2S3 [18] show visible photoresponse while InGaAs [19], InAs [20] and Cd3P2 [21] are good for NIR light
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