Abstract
Cu-Zn-Sn-Te (CZTTe) is an inexpensive quaternary semiconductor that has not been investigated so far, unlike its intensively studied CZTS and CZTSe counterparts, although it may potentially have desirable properties for solar energy conversion, thermoelectric, and other applications. Here, we report on the synthesis of CZTTe nanocrystals (NCs) via an original low-cost, low-temperature colloidal synthesis in water, using a small-molecule stabilizer, thioglycolic acid. The absorption edge at about 0.8–0.9 eV agrees well with the value expected for Cu2ZnSnTe4, thus suggesting CZTTe to be an affordable alternative for IR photodetectors and solar cells. As the main method of structural characterization multi-wavelength resonant Raman spectroscopy was used complemented by TEM, XRD, XPS as well as UV-vis and IR absorption spectroscopy. The experimental study is supported by first principles density functional calculations of the electronic structure and phonon spectra. Even though the composition of NCs exhibits a noticeable deviation from the Cu2ZnSnTe4 stoichiometry, a common feature of multinary NCs synthesized in water, the Raman spectra reveal very small widths of the main phonon peak and also multi-phonon scattering processes up to the fourth order. These factors imply a very good crystallinity of the NCs, which is further confirmed by high-resolution TEM.
Highlights
The growing demand for clean, renewable, and portable energy sources inspires the search for materials with suitable structural characteristics and appropriate parameters of charge generation and transport, thermal transport, and optical properties
In the course of the reaction that formed Cu-Sn-Zn-Te NCs stabilized with thioglycolic acid (TGA), the color of the solution changes from grey to black
A route for the synthesis of Cu-Zn-Sn-Te (CZTTe) NCs by an original low-cost method based on a low-temperature colloidal synthesis in water, using a small-molecule stabilizer, thioglycolic acid (TGA), is proposed
Summary
The growing demand for clean, renewable, and portable energy sources inspires the search for materials with suitable structural characteristics and appropriate parameters of charge generation and transport, thermal transport, and optical properties. A vast playground for tuning the properties for various applications is the family of quaternary chalcogenides I2 -III-IV-VI4 It is well known that among binary and ternary chalcogenides the tellurides are generally more promising for thermoelectric applications [10], while the red-shifted bandgap of quaternary telluride compared to sulphides and selenides can be advantageous for photovoltaics [11,12]. Contrary to intensively investigated sulphides and selenides, as indicated by thousands of publications so far, including numerous. [18], this compound was synthesized by a traditional solid-state tube method and ball-milling, and its thermoelectric (TE) properties were investigated. The thermoelectric properties of bulk Cu2 ZnSnTe4 were investigated in Ref. The thermoelectric properties of bulk Cu2 ZnSnTe4 were investigated in Ref. [19]
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