Size control and quantum confinement in Cu2ZnSnS4 nanocrystals
ABSTRACT Starting with metal dithiocarbamate complexes, we synthesize colloidal Cu(2)ZnSnS(4) (CZTS) nanocrystals with diameters ranging from 2 to 7 nm. Structural and Raman scattering data confirm that CZTS is obtained rather than other possible material phases. The optical absorption spectra of nanocrystals with diameters less than 3 nm show a shift to higher energy due to quantum confinement.
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- "The black precipitate formed was filtered and washed multiple times with ultra-high pure water and dried in desiccators. Cu(dedc ) 2 crystals were dried in vacuum overnight before further use (Khare et al 2011). "
ABSTRACT: Size-controlled CZTS quantum dots (QDs) were synthesized and its application as a potential electron accepting material for polymer-based hybrid solar cell is demonstrated. The CZTS QDs with a size of 2–10 nm were synthesized in a single step by the decomposition of metal dithiocarbamate and characterized by various techniques; like, SEM, TEM, FTIR, XRD, etc. Results reveal that the CZTS QDs synthesized in oleic acid can quench the luminescence of P3HT effectively. Due to the favourable ionization potential and electron affinity values for CZTS with respect to P3HT, the CZTS QDs act as an effective electron acceptor in the hybrid solar cells based on P3HT/CZTS-QD blends which is also revealed by the charge transfer characteristics of P3HT/CZTS blend.02/2015; DOI:10.1007/s13204-015-0404-z
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- "The bandgap of CZTSe NCs was estimated to be 1.76 eV by extrapolating the linear region of a plot of the squared absorbance versus the photon energy. This is mainly attributed to the small size and quantum confinement effect of CTZSe NCs . "
ABSTRACT: In this work, we employed a convenient one-step synthesis method for synthesizing Cu2ZnSnSe4 (CZTSe) nanocrystals (NCs) in an excess selenium environment. This excess selenium situation enhanced the reaction of metal acetylacetonates with selenium, resulting in the burst nucleation of NCs at relatively low temperatures. The phase morphology and surface and optoelectronic properties of NCs before and after ligand exchange were discussed in depth. It was found that pure tetragonal-phase structure CZTSe NCs with approximately 1.7-eV bandgap could be synthesized. The removal of large organic molecules on CZTSe NCs after ligand exchange by S(2-) decreased the resistivity. The bandgap of the films after ligand exchange by 550°C selenization was also decreased due to better crystallinity. For potential application in CZTSe solar cells, we constructed an energy level diagram to explain the mutual effect between the absorption layer and CdS layer. Using cyclic voltammetry (CV) measurement, we found that the highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) energy levels of CZTSe films shifted down after ligand exchange. After energy level alignment at the CdS/CZTSe interface, a type I band alignment structure was more conveniently formed after ligand exchange. This structure acted as the barrier against injection electrons from ZnO to the CZTSe layer, and recombination would subsequently be depressed.Nanoscale Research Letters 05/2014; 9(1-1):262. DOI:10.1186/1556-276X-9-262 · 2.78 Impact Factor
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ABSTRACT: Quaternary tetragonal Cu(2)FeSnS(4) nanocrystals have been synthesized by a simple hot-injection method. Detailed characterizations have been made. A suitable optical band gap of 1.28 ± 0.02 eV and a notable and stable photoelectrochemical response indicate their potential for application in solar cells.Chemical Communications 02/2012; 48(20):2603-5. DOI:10.1039/c2cc16972j · 6.83 Impact Factor