**1. Introduction**

Metal sulfides have received considerable interest due to their unique optoelectronic properties while processed at micro-nano level [1–4]. In particular, two-dimensional (2D) metal sulfides nanostructures such as nanoplates, nanoflakes and nanosheets have received much attention for their potential application in photodetectors, photovoltaic devices and light-emitting diodes [5–20]. 2D form of the material o ffers high specific surface area, making it advantageous for electrochemical, catalytic and photoelectrical activities. Another advantage in 2D materials is that they are more compatible and can easily be integrated into nano-microscale structures for developing new optoelectronic devices [21–24].

Meanwhile, SnS2 is considered as one of the promising layered materials with excellent visible light absorption and electrical properties. It possesses band gap (2.1–2.3 eV), n-type characteristics, high sensitivity and high surface activity for applications in Li-ion batteries [25], photovoltaic devices [26] and photodetector [27,28]. Variety of nanostructures such as nanoflakes, nanosheets and nanoplates through physical and chemical techniques including chemical vapor deposition, solvothermal and hydrothermal methods have been reported by several groups [29,30]. Among them, nanoflakes preparation via hydrothermal method have attracted considerable interest due to its low cost and large-scale production at low temperatures. Similarly, many e fforts have also been made in controlling morphology and enhancing the photoelectrical, chemical and physical properties for improving the device performance. Moreover, dopants in semiconductor could lead to reduction in particle size, narrowing of band gap and enhance the photoelectrical properties of SnS2 [31]. Recently, V and

Ti doped SnS2 was reported to be an intermediate band material for application in wider solar absorption [32,33]. Recently doping SnS2 with Fe resulted in room temperature ferromagnetism [34]. Similarly, in our previous work, we reported enhanced optical and electrical properties of SnS2 nanoflakes via Cu doping [35]. More recently, Liu et al. reported enhanced photoresponsivity in Sb doped SnS2 monolayer [36]. Based on the above literatures we test the ability of doping Zn ions in SnS2 to significantly enhance conductivity and sensitivity favorable for its performance in photoelectronics.

The present work reports on hydrothermal synthesis of Zn doped SnS2 nanoflakes at low temperatures. The properties of Sn1−*<sup>x</sup>*Zn*x*S2 nanoflakes have been intensively studied through structural, optical and photoelectrical methods. The results show that the Zn doping results in enhanced sensitivity, conductivity and e fficiency of charge transfer kinetics. As a proof of concept, Sn1−*<sup>x</sup>*Zn*x*S2 nanoflakes were integrated into a patterned indium tin oxide (ITO) substrate (as active material) for photoelectronic device architecture. The results showcased excellent on-o ff ratio and photoresponse properties than that of pristine counterpart. Our investigations presents Zn doped SnS2 could be a potential candidate for future nano electronic and photoelectronic applications.
