Structure and optical properties of sequentially electrodeposited ZnO/Se bases for ETA solar cells N.P. Klochko a , K.S. Klepikova a , I.I. Tyukhov b,⇑ , Y.O. Myagchenko c , E.E. Melnychuk c , V.R. Kopach a , G.S. Khrypunov a , V.M. Lyubov a , A.V. Kopach a a National Technical University “Kharkiv Polytechnic Institute”, 21, Frunze str., 61002 Kharkiv, Ukraine b All-Russian Research Institute for Electrification of Agriculture (VIESH), 2, 1-st Veschnyakovsky proezd, 109456 Moscow, Russian Federation c National Taras Shevchenko University, 62, Volodymyrska str., 03680 Kyiv, Ukraine Received 31 May 2015; received in revised form 14 July 2015; accepted 23 July 2015 Communicated by: Associate Editor Takhir M. Razykov Abstract For a development of base layers for promising solar cells with extremely thin absorbers (ETA) low cost electrodeposition methods for sequential large-scale production of one-dimensional ZnO nanostructures and Se thin films with little material waste were investi- gated. Research of structure and optical properties of Se and ZnO have allowed us to choose electrolytes and modes in which electrode- position of selenium was not accompanied by ZnO destruction. It was revealed that annealing of ZnO/Se samples using a halogen lamp provides conversion of amorphous selenious films into suitable for solar cells gray nanocrystalline hexagonal Se without ZnO degrada- tion and thus enables the formation of bases of ETA solar cells. Ó 2015 Elsevier Ltd. All rights reserved. Keywords: Pulse electrodeposition; Selenium; Solar cell; Zinc oxide 1. Introduction The increased global demand for low-cost renewable energy sources has motivated researchers to derive and explore novel methods for utilization of solar energy. Among these methods, photovoltaic is one of the clean technologies that have been adopted to produce electricity by means of solar cells. However, low efficiency, high cost associated with the preparation of materials and sub- sequent device fabrication prevented their extensive use to satisfy the growing demand. Nanocrystalline thin film solar cells based on nanostructured morphologies of metal oxi- des, especially TiO 2 and ZnO, with high surface area are gaining momentum as potential low-cost photovoltaic cells, due to the availability of their constituent materials and relatively cheap construction processes (Page et al., 2009; Nazeeruddin et al., 2011; Babu et al., 2014; Nikhil et al., 2014). One promising concept is the extremely thin absorber (ETA) class of solar cells, in which an ultra-thin light-absorbing semiconductor layer is deposited on the large branched or one-dimensional (1-D) surface of the oxide film, completed with an appropriate wide band gap p-type semiconducting thin film as a hole conductor. The stated goal of the ETA concept is to allow relatively low quality materials to be employed, due to the short distance through which photogenerated carriers need to be transported before being separated into the respective http://dx.doi.org/10.1016/j.solener.2015.07.038 0038-092X/Ó 2015 Elsevier Ltd. All rights reserved. ⇑ Corresponding author at: UNESCO Chair, The All-Russian Research Institute for Electrification of Agriculture (VIESH), 2, 1-st Veschnya- kovsky proezd, 109456 Moscow, Russian Federation. Tel.: +7 (499) 171 05 23, +7 (499) 171 19 20; fax: +7 (499)170 51 01. E-mail addresses: viesh@dol.ru, ityukhov@yahoo.com (I.I. Tyukhov). URL: http://www.viesh.ru/ (I.I. Tyukhov). www.elsevier.com/locate/solener Available online at www.sciencedirect.com ScienceDirect Solar Energy 120 (2015) 330–336