Contents lists available at ScienceDirect Solar Energy journal homepage: www.elsevier.com/locate/solener Photoelectrochemical performance of spray-deposited Fe-doped ZnS 0.2 Se 0.8 thin films Nandkishor M. Patil, Santosh G. Nilange, Abhijit A. Yadav ⁎ Thin Film Physics Laboratory, Department of Physics, Electronics and Photonics, Rajarshi Shahu Mahavidyalaya, Latur (Autonomous) 413512, Maharashtra, India ARTICLE INFO Keywords: Doping N-type conductivity PEC cell parameters Barrier height Spectral response ABSTRACT Binary and ternary II–VI group semiconductor compounds are materials with potential use in various optoe- lectronic applications, including photoelectrochemical (PEC) solar cells. Thin films of ZnS 0.2 Se 0.8 with various Fe-doping concentrations were successfully deposited on fluorine-doped tin oxide-coated glass substrates at a deposition temperature of 275 °C using the chemical spray pyrolysis. PEC cells with Fe:ZnS 0.2 Se 0.8 thin film/1 M polysulphide/C (graphite) configurations were designed, and the effect of Fe doping on the PEC performance was studied. The results showed that Fe doping in ZnS 0.2 Se 0.8 enhanced the performance of the PEC cells sig- nificantly. The optimum concentration was 0.20 mol%. The flat band potential and junction barrier height were maximum at this concentration, with values of -1.18 V and 0.27 eV, respectively. The junction ideality factors of the 0.20 mol% Fe-doped ZnS 0.2 Se 0.8 thin film-based PEC cell in the dark and under illumination were found to be 1.21 and 1.17, respectively. The photovoltaic power output characteristics were boosted by Fe doping with a concentration of 0.20 mol%, with the open circuit voltage being 320 mV and the short circuit current being 1.48 mA cm -2 . The solar-to-electrical conversion and the fill factor of the 0.20 mol% Fe-doped ZnS 0.2 Se 0.8 thin film-based PEC cells were superior, with values of 2.84% and 0.60, respectively. A PEC cell with a 0.20 mol% Fe- doped ZnS 0.2 Se 0.8 photosensitive thin film had the highest spectral sensitivity, at a wavelength of 375 nm, with an optical band gap of 3.30 eV. 1. Introduction Energy is necessary for any living creature. It is a vital element of human life, playing a crucial role in the socio-economic development of the world. Today, the world power utilization is approximately 13 TW, more than 80% of which is generated from non-renewable energy sources such as coal, oil, and natural gas. The worldwide energy de- mand has been accelerating at an alarming rate, rapidly depleting fossil fuel-based energy stocks and driving a search for clean and safe alter- native energy sources. Solar energy is one of the most promising available renewable energy sources, the use of which involves the conversion of light energy directly to electrical energy. It is freely available, abundant, and environment-friendly (carbon-free). The solar energy available is approximately 10,000 times more than the annual energy requirements of the world (Iqbal and Rehman, 2018; Liu and Wang, 2019; Arutyunov and Lisichkin, 2017). Thus it is important to search for and develop solar energy conversion technologies that are efficient, simple, affordable, clean, and eco-friendly in order to meet present and future green energy demands (Karim et al., 2019). There are two types of semiconductor-based solar cells: solid–solid junction solar cells and solid–liquid junction solar cells. The photo- electrochemical cell (PEC) is a simple type of solar cell in which a so- lid–liquid junction can be utilized for the energy conversion. PEC de- vices are affordable and easy to fabricate. PEC cells are promising devices. It might be possible to develop inexpensive photovoltaic panels by enhancing the power conservation efficiency of PEC devices. Thus many researchers have worked on the use of PEC techniques for elec- tricity generation (Baig et al., 2019; Hodes, 1980; Ansari et al., 2019). The semiconducting material is a key component in a PEC solar cell. It absorbs incident photons and creates electron–hole pairs (van de Krol, 2018). II–VI group semiconducting materials, with broad direct optical band gaps, have excellent optical and electrical properties that are suitable for the fabrication of many optoelectronic devices such as photovoltaic cells and PEC cells (Isshiki and Wang, 2017; Manivannan and Noyel Victoria, 2018). Among the various II–VI group semi- conductors, ZnS- and ZnSe-based binary and ternary compounds have been found to be important materials for fabrication of optoelectronic devices (Fard and Dehghani, 2019; Bechiri et al., 2009). ZnS x Se 1-x are important ternary compounds that have received a lot of attention because they offer the possibility of tuning significant parameters such https://doi.org/10.1016/j.solener.2019.08.052 Received 7 July 2019; Received in revised form 14 August 2019; Accepted 20 August 2019 ⁎ Corresponding author. E-mail address: aay_physics@yahoo.co.in (A.A. Yadav). Solar Energy 191 (2019) 1–6 0038-092X/ © 2019 International Solar Energy Society. Published by Elsevier Ltd. All rights reserved. T