Cadmium effect on optical properties of Cu 2 Zn 1x Cd x SnS 4 quinternary alloys nanostructures A.S. Ibraheam a , Y. Al-Douri a,e,⇑ , U. Hashim a , M.R. Ghezzar b , A. Addou c , Waleed K. Ahmed d a Institute of Nano Electronic Engineering, University Malaysia Perlis, 01000 Kangar, Perlis, Malaysia b Laboratoire de Ge ´nie des Proce ´de ´ s Plasma et traitement de surface, UPMC Universite ´ de Paris 06, 11 rue Pierre et Marie Curie 75005, France c Laboratoire des Sciences et Techniques de l’Environnement et de la Valorisation, Universite ´ de Mostaganem, 27000, Algeria d ERU, Faculty of Engineering, United Arab Emirates University, Al Ain, United Arab Emirates e Physics Department, Faculty of Science, University of Sidi-Bel-Abbes, 22000, Algeria Received 17 November 2014; received in revised form 8 January 2015; accepted 15 January 2015 Communicated by: Associate Editor Takhir M. Razykov Abstract While efforts have been made to synthesize quaternary alloy nanostructures with high surface area for application in many fields, a detailed exploration of quinternary alloy nanostructures has not been reported until now. This work investigates the optimum crystal- lization parameters for reducing crystal defects in Cu 2 Zn 1x Cd x SnS 4 quinternary alloy nanostructures. Alloy nanostructures with differ- ent Zn and Cd contents were grown by a sol–gel method. The analytical results confirmed a multi-phase polycrystallinity of the samples, and the variations in their energetic transitions and optical properties with Cd content were investigated. The morphology and topog- raphy of the samples were also observed. Our results are supported by several related studies in the literature. Ó 2015 Elsevier Ltd. All rights reserved. Keywords: Quinternary alloy; Nanostructure; Sol–gel method; Synthesis 1. Introduction Nanostructured Cu 2 ZnSnS 4 (CZTS) quaternary alloy has a band gap in the visible light region, 1.5 eV, and an optical absorption coefficient of 10 4 cm 1 . It is composed of earth-abundant cheap and non-toxic elements (Feser et al., 2013; Yang et al., 2012; Tanaka et al., 2014; Ge et al., 2014; Service, 2010; Reshak et al., 2014). The struc- ture of CZTS makes it a promising replacement material for CuIn 1x Ga x Se 2 (CIGS) and CdTe in solar cells by replacing In with Zn, Ga with Sn, and Se with S (Singh et al., 2012; Gurav et al., 2014; Kang et al., 2013). Although quaternary CZTS alloy crystallizes in the keste- rite structure, the possible existence of Stannite structure cannot be ruled out because the two structures differ only in the positions of the copper and zinc elements (Shi et al., 2013; Kabalah-Amitai et al., 2013; Malerba et al., 2014; Michael et al., 2013). The metastable wurtzite phase of CZTS has been synthesized in the form of nanocrystals. The crystallization of CZTS generally offers flexibility over stoichiometry control and also facilitates the nanocrystals to grow in 1D morphology along the anisotropic c-axis direction (Fan et al., 2014; Bai and Liu, 2012). Recently Dhakal et al. (2014) have reported on a Cu 2 - ZnSnS 4 (CZTS) thin film solar cell that showed an efficiency of about 6.2% without an anti-reflection coating. Initially, their CZTS precursor film was co-sputtered using three http://dx.doi.org/10.1016/j.solener.2015.01.018 0038-092X/Ó 2015 Elsevier Ltd. All rights reserved. ⇑ Corresponding author. Tel.: +60 49775021; fax: +60 49798578. E-mail address: yaldouri@yahoo.com (Y. Al-Douri). www.elsevier.com/locate/solener Available online at www.sciencedirect.com ScienceDirect Solar Energy 114 (2015) 39–50