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Ternary SnS(2-x)Se(x) Alloys Nanosheets and Nanosheet Assemblies with Tunable Chemical Compositions and Band Gaps for Photodetector Applications.

Yu J, Xu CY, Li Y, Zhou F, Chen XS, Hu PA, Zhen L - Sci Rep (2015)

Bottom Line: The variation tendency of band gap was also confirmed by first-principles calculations.The photoelectrochemical measurements indicate that the performance of ternary SnS(2-x)Se(x) alloys depends on their band structures and morphology characteristics.Furthermore, SnS(2-x)Se(x) photodetectors present high photoresponsivity with a maximum of 35 mA W(-1) and good light stability in a wide range of spectral response from ultraviolet to visible light, which renders them promising candidates for a variety of optoelectronic applications.

View Article: PubMed Central - PubMed

Affiliation: School of Materials Science and Engineering, Harbin Institute of Technology, Harbin 150001, China.

ABSTRACT
Ternary metal dichalcogenides alloys exhibit compositionally tunable optical properties and electronic structure, and therefore, band gap engineering by controllable doping would provide a powerful approach to promote their physical and chemical properties. Herein we obtained ternary SnS(2-x)Se(x) alloys with tunable chemical compositions and optical properties via a simple one-step solvothermal process. Raman scattering and UV-vis-NIR absorption spectra reveal the composition-related optical features, and the band gaps can be discretely modulated from 2.23 to 1.29 eV with the increase of Se content. The variation tendency of band gap was also confirmed by first-principles calculations. The change of composition results in the difference of crystal structure as well as morphology for SnS(2-x)Se(x) solid solution, namely, nanosheets assemblies or nanosheet. The photoelectrochemical measurements indicate that the performance of ternary SnS(2-x)Se(x) alloys depends on their band structures and morphology characteristics. Furthermore, SnS(2-x)Se(x) photodetectors present high photoresponsivity with a maximum of 35 mA W(-1) and good light stability in a wide range of spectral response from ultraviolet to visible light, which renders them promising candidates for a variety of optoelectronic applications.

No MeSH data available.


(a) Calculated band structure of SnS0.44Se1.56 alloy. (b) The total and partial density of states of SnS0.44Se1.56.
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f5: (a) Calculated band structure of SnS0.44Se1.56 alloy. (b) The total and partial density of states of SnS0.44Se1.56.

Mentions: For further theoretical study, we employed first principles calculations to obtain the band gap structures and DOS curves, which are benefit to analyze the electronic structures of SnS2−xSex alloys and possible affecting factors. Figure 5 shows the first-principles calculations results of SnS0.44Se1.56 alloy. The corresponding band structure is shown in Fig. 5a, which clearly demonstrates SnS0.44Se1.56 is an indirect band gap semiconductor. The band gap of SnS0.44Se1.56 is calculated to be 1.421 eV, which is in good accordance with the experimental value of 1.39 eV. Additionally, the band gaps of pure SnS2 and SnSe2 were estimated to be 2.461 and 1.402 eV, respectively (Supplementary Fig. S7), which are close to the experimental values of 2.23 and 1.29 eV. The calculated results roughly reveal the variation tendency of band gaps with the increase of Se concentration in SnS2−xSex crystals, which might be ascribed to the replacement of S and Se, affecting electronic structure distribution in the alloy system37. The total and partial density of states (TDOS and PDOS) of SnS0.44Se1.56 are provided in Fig. 5b, and the energy zero is defined as Fermi energy level. From Fig. 5b, we could conclude the contribution of different orbitals to VB and CB SnS0.44Se1.56 alloy. PDOS curves actually presented different tendencies in the regions close to the VB and CB. The states near VB are dominated by the S 3p and Se 4p orbitals, while CB is mainly composed of hybridized states of Sn 5s, S 3p and Se 4p orbitals. The difference of constituting orbitals in VB and CB would result in the dissimilarities of band structure in SnS2−xSex alloys with the change of S/Se ratio.


Ternary SnS(2-x)Se(x) Alloys Nanosheets and Nanosheet Assemblies with Tunable Chemical Compositions and Band Gaps for Photodetector Applications.

Yu J, Xu CY, Li Y, Zhou F, Chen XS, Hu PA, Zhen L - Sci Rep (2015)

(a) Calculated band structure of SnS0.44Se1.56 alloy. (b) The total and partial density of states of SnS0.44Se1.56.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4663750&req=5

f5: (a) Calculated band structure of SnS0.44Se1.56 alloy. (b) The total and partial density of states of SnS0.44Se1.56.
Mentions: For further theoretical study, we employed first principles calculations to obtain the band gap structures and DOS curves, which are benefit to analyze the electronic structures of SnS2−xSex alloys and possible affecting factors. Figure 5 shows the first-principles calculations results of SnS0.44Se1.56 alloy. The corresponding band structure is shown in Fig. 5a, which clearly demonstrates SnS0.44Se1.56 is an indirect band gap semiconductor. The band gap of SnS0.44Se1.56 is calculated to be 1.421 eV, which is in good accordance with the experimental value of 1.39 eV. Additionally, the band gaps of pure SnS2 and SnSe2 were estimated to be 2.461 and 1.402 eV, respectively (Supplementary Fig. S7), which are close to the experimental values of 2.23 and 1.29 eV. The calculated results roughly reveal the variation tendency of band gaps with the increase of Se concentration in SnS2−xSex crystals, which might be ascribed to the replacement of S and Se, affecting electronic structure distribution in the alloy system37. The total and partial density of states (TDOS and PDOS) of SnS0.44Se1.56 are provided in Fig. 5b, and the energy zero is defined as Fermi energy level. From Fig. 5b, we could conclude the contribution of different orbitals to VB and CB SnS0.44Se1.56 alloy. PDOS curves actually presented different tendencies in the regions close to the VB and CB. The states near VB are dominated by the S 3p and Se 4p orbitals, while CB is mainly composed of hybridized states of Sn 5s, S 3p and Se 4p orbitals. The difference of constituting orbitals in VB and CB would result in the dissimilarities of band structure in SnS2−xSex alloys with the change of S/Se ratio.

Bottom Line: The variation tendency of band gap was also confirmed by first-principles calculations.The photoelectrochemical measurements indicate that the performance of ternary SnS(2-x)Se(x) alloys depends on their band structures and morphology characteristics.Furthermore, SnS(2-x)Se(x) photodetectors present high photoresponsivity with a maximum of 35 mA W(-1) and good light stability in a wide range of spectral response from ultraviolet to visible light, which renders them promising candidates for a variety of optoelectronic applications.

View Article: PubMed Central - PubMed

Affiliation: School of Materials Science and Engineering, Harbin Institute of Technology, Harbin 150001, China.

ABSTRACT
Ternary metal dichalcogenides alloys exhibit compositionally tunable optical properties and electronic structure, and therefore, band gap engineering by controllable doping would provide a powerful approach to promote their physical and chemical properties. Herein we obtained ternary SnS(2-x)Se(x) alloys with tunable chemical compositions and optical properties via a simple one-step solvothermal process. Raman scattering and UV-vis-NIR absorption spectra reveal the composition-related optical features, and the band gaps can be discretely modulated from 2.23 to 1.29 eV with the increase of Se content. The variation tendency of band gap was also confirmed by first-principles calculations. The change of composition results in the difference of crystal structure as well as morphology for SnS(2-x)Se(x) solid solution, namely, nanosheets assemblies or nanosheet. The photoelectrochemical measurements indicate that the performance of ternary SnS(2-x)Se(x) alloys depends on their band structures and morphology characteristics. Furthermore, SnS(2-x)Se(x) photodetectors present high photoresponsivity with a maximum of 35 mA W(-1) and good light stability in a wide range of spectral response from ultraviolet to visible light, which renders them promising candidates for a variety of optoelectronic applications.

No MeSH data available.