**4. Conclusions**

In summary, Sn0.97Zn0.03S2 nanoflakes were prepared via low temperature hydrothermal synthesis. The modulation of the structural and photoelectrical properties in SnS2 via doping Zinc have been discussed in detail. A shift in XPS peak of Sn 3d5/2 and S 2p3/2 has been observed in Sn0.97Zn0.03S2 nanoflakes due to Zn ion replaced Sn sites in the SnS2 crystal lattice. Optical properties studies show that Sn0.97Zn0.03S2 nanoflakes possess higher visible-light absorption than that of pristine SnS2. Photoelectrical properties based on Sn0.97Zn0.03S2 nanoflakes reveal that Zn doping leads to significant improvement in conductivity and sensitivity to illuminations compared to pristine SnS2. Such an excellent performance of Sn0.97Zn0.03S2 nanoflakes may endow it as a potential candidate for emerging 2D materials in optoelectronic applications.

**Supplementary Materials:** The following are available online at http://www.mdpi.com/2079-4991/9/7/924/s1, Figure S1: SEM image of Sn0.99Zn0.01S2 nanoflakes, Figure S2: Mott–Schottky plot of Sn0.99Zn0.01S2 nanoflakes.

**Author Contributions:** Conceptualization: G.M.K. and P.I.; data curation, G.M.K., H.D.C., H.C.J. and P.I.; supervision, T.W.K.; validation, G.M.K. and S.Y.; visualization, T.W.K. and D.Y.K.; writing—original draft, P.I.; all authors read and approved the final manuscript.

**Acknowledgments:** This work was supported by the Basic Science Research Program through the National Research Foundation of Korea (NRF) gran<sup>t</sup> funded by the Ministry of Education (no. 2018R1D1A1B07051461, no. 2018R1D1A1B07051474, no. 2018R1D1A1B07051406, no. 2018R1D1A1B07050237, no. 2018R1D1A1B07051095, no. 2017R1D1A1B03032759 and no. 2016R1A6A1A1A01012877).

**Conflicts of Interest:** The authors declare no conflict of interest.
