A High Yield Synthesis of Chalcopyrite CuInS2 Nanoparticles with Exceptional Size Control
Various I-III-VI2 semiconductor materials have been identified as promising photovoltaic materials [1, 2]. Recently, quantum dot (QD) based solar cells have attracted much attention due to their potential to replace thin film devices [3-5]. One of the major advantages of employing QDs is by simply changing the particle size they can be tuned to absorb specific wavelengths ranging from visible to infrared wavelengths [6]. Furthermore, with careful design of photovoltaic (PV) devices incorporating various sizes of nanoparticles in multiple layers, one may achieve increased solar energy absorption in one device [7, 8]. In order to facilitate QD based multilayer devices, synthetic strategies that can deliver QDs in high yields with precise size control are essential. One of the strategies to prepare QDs is to prepare nanoparticles from molecular single source precursors (SSPs), which contain all necessary elements in a single molecule. In recent years, there have been several reports on the formation of CuInS2 nanoparticles through the decomposition of SSPs using thermolysis [9-14], photolysis [18], and microwave irradiation [16]. However, many of these procedures require a combination of long reaction times (10 to 24 hours) and high reaction temperatures (often exceeding 200 °C) with very little information regarding overall yields. Microwave-assisted growth of nanoparticles is generally favorable over traditional thermolysis as microwave irradiation overcomes local intermediaries and increases the microscopic temperature of the reaction [17] thus exhibiting greater homogeneity in the overall reaction temperature. This allows for nanoparticles with diameters of a few nanometers can be prepared [18], dramatic decreases in reaction times, improved product purities, all forms of precursors can be used, and reactions exhibit high reproducibility and yields [19]. For CuInS2 QDs, the Wannier-Mott bulk exciton radius is approximately 8 nm with a bandgap of 1.45 eV and QDs with radii smaller than 8 nm exhibit bandgaps greater than 1.45 eV [20]. Our group has recently reported the synthesis of CuInS2 nanoparticles using SSPs via microwave irradiation with 1-hexanethiol as a surface pacifying ligand to afford nanoparticle sizes ranging from 3 to 5 nm [16]. Herein, we report efficient size controlled syntheses of Chalcopyrite CuInS2 nanoparticles by decomposition of SSPs in the presence of 1,2-ethanedithiol with extraordinarily high yields. The titration studies by 1H NMR using SSP 1 with 1,2-ethanedithiol and benzyl mercaptan are conducted to elucidate the formation of Chalcopyrite CuInS2 nanoparticles.
- Research Organization:
- Pacific Northwest National Lab. (PNNL), Richland, WA (United States). Environmental Molecular Sciences Lab. (EMSL)
- Sponsoring Organization:
- USDOE
- DOE Contract Number:
- AC05-76RL01830
- OSTI ID:
- 977325
- Report Number(s):
- PNNL-SA-68507; 17795; KP1704020; TRN: US201013%%468
- Journal Information:
- Journal of Nanomaterials, 2009:Article No. 748567, Journal Name: Journal of Nanomaterials, 2009:Article No. 748567
- Country of Publication:
- United States
- Language:
- English
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