Contents lists available at ScienceDirect Solar Energy journal homepage: www.elsevier.com/locate/solener Fabrication and performance analysis of a low cost, Pt free counter electrode using carbon coated ZnAl layered double hydroxide (C/ZnAl-LDH) for dye sensitized solar cells Giphin George, M.P. Saravanakumar ⁎ Department of Environmental and Water Resources Engineering, School of Civil Engineering, Vellore Institute of Technology, Vellore Campus, India ARTICLE INFO Keywords: Carbon based material Layered double hydroxides Counter electrode Electrochemical parameters Dye Sensitized Solar Cell ABSTRACT Carbon based material represents an effective substitute for Pt counter electrodes (CEs) in Dye Sensitized Solar Cells (DSSCs). This study introduces a novel carbon coated ZnAl layered double hydroxides (C/ZnAl-LDH) can be utilised as an effective CE in DSSCs. C/ZnAl-LDH was synthesised by the pyrolysis of ZnAl-LDH using glucose solution. The synthesised C/ZnAl-LDH was characterised using TEM, SEM, XRD and BET analysis. The surface roughness of both Pt and C/ZnAl-LDH films were analysed using AFM spectroscopy. C/ZnAl-LDH slurry was pasted uniformly using doctor blade technique onto FTO glass substrate. The electrochemical measurements such as Cyclic Voltammetry (CV), Electrochemical Impedance Spectroscopy (EIS) and Tafel polarization re- commends that C/ZnAl-LDH can be used as a CE due to its good reduction rate of − I 3 comparable with Pt CEs. The photovoltaic parameters were observed to be 0.66 V and 11.97 mA/cm 2 for open circuit voltage V ( ) oc and short circuit current density J ( ) sc respectively for C/ZnAl-LDH CE. The assembled cell with C/ZnAl LDH CE having power conversion efficiency (PCE) of 3.18% is comparable to Pt CE having 4.62% which is measured under the similar testing conditions. 1. Introduction Dye Sensitized Solar Cells (DSSCs) having more significant im- portance due to their ability for higher power conversion efficiency (PCE), considering as a good substitute for silicon solar cells (O’Regan and Gratzel, 1991). DSSC contains three main components, a titanium oxide (TiO 2 ) layer called as photo anode, a counter electrode (CE) and an iodine/triiodide electrolyte kept among the photo anode and counter electrode (Tang et al., 2013). An effective CE must having properties like chemical stability, good electrical conductivity and high electro catalytic activity (Kumar et al., 2017). Usually Platinum (Pt) coated FTO glass slide was utilised as CE in DSSC. Pt possess good catalytic activity for redox reaction and having excellent electrical conductivity (Mehmood et al., 2016). But the main drawback using Pt as counter electrode is its huge cost and fast degradation while reacting with − I / − I 3 electrolyte (Yun et al., 2015b, 2015a). So that, many researchers are now focusing to develop an alternative materials for Pt electrodes (Chen and Shao, 2016; Theerthagiri et al., 2015). There are several low cost substances like carbon based materials (Miao et al., 2013; Murakami et al., 2006; Theerthagiri et al., 2017), metal carbides (Wu et al., 2012), metal oxide (Guai et al., 2012), alloys (Barakat et al., 2012), conducting polymers (Ke et al., 2015; Lin et al., 2016; Park et al., 2015), transition metal based substances like metal sulphides (Chi et al., 2012; Theerthagiri et al., 2016a), metal nitrides (Jiang et al., 2010, 2009; Li et al., 2011) and metal selenides (Theerthagiri et al., 2016b) were used as good CEs and resulted ex- cellent catalytic activity towards redox electrolytes. For the manu- facturing of a low cost DSSC, it is essential to use an abundant and inexpensive material as the counter electrode, that can replace Pt in DSSCs. Carbon, one among the most plentiful substances in the Earth's surface, is a good material that can be used as a substitute for Pt. Mostly because of its essential characteristics like low cost, good electrical conductivity, environmental friendly, high thermal stability, corrosion resistance, availability and high reactivity towards − I / − I 3 redox elec- trolyte, carbon is a better option (Thomas et al., 2014). So far many researchers have used carbon materials namely mesoporous carbon, graphite, carbon black, graphene, carbon nanotubes (CNTs), activated carbon and carbon composites which can be used as a substitute for Pt CEs (Kim et al., 2018; Theerthagiri et al., 2016c; Torres et al., 2019). Recently (Ma et al., 2019) synthesised a Fe-Co nanoparticle-in- corporated carbon nanofibers by electrospinning method and utilised as CE for platinum free DSSC. In that work they obtained a PCE of 3.91% https://doi.org/10.1016/j.solener.2020.03.113 Received 31 October 2019; Received in revised form 20 March 2020; Accepted 30 March 2020 ⁎ Corresponding author. E-mail address: saravanakumar05@gmail.com (M.P. Saravanakumar). Solar Energy 202 (2020) 144–154 0038-092X/ © 2020 International Solar Energy Society. Published by Elsevier Ltd. All rights reserved. T