Quantum dot solar concentrators: Electrical conversion efficiencies and comparative concentrating factors of fabricated devices S.J. Gallagher a, * , B. Norton a , P.C. Eames b a Focas Institute, School of Physics, Dublin Institute of Technology, Kevin St, Dublin 8, Ireland b School of Engineering, University of Warwick, Coventry CV4 7AL, United Kingdom Received 17 February 2006; received in revised form 11 August 2006; accepted 14 September 2006 Available online 7 November 2006 Communicated by: Associate Editor Arturo Morales-Acevedo Abstract A novel, non-tracking concentrator is described, which uses nano-scale quantum dot technology to render the concept of a fluorescent dye solar concentrator (FSC) a practical proposition. The quantum dot solar concentrator (QDSC) comprises quantum dots (QDs) seeded in materials such as plastics and glasses that are suitable for incorporation into building fac ¸ades. Photovoltaic (PV) cells attached to the edges convert direct and diffuse solar energy collected into electricity for use in the building. Small scale QDSC devices were fab- ricated. Devices have been characterised to determine current, voltage and power readings. Electrical conversion efficiencies, fill factors and comparative concentrating factors are reported. Ó 2006 Elsevier Ltd. All rights reserved. Keywords: Quantum dot; Solar concentration; Fluorescence; Photovoltaic cell; Non-imaging concentrator 1. Introduction Buildings typically account for 20–30% of the total pri- mary energy requirements of industrialised countries (Sick and Erge, 1996), approximately 40% in the EU and 46% in Ireland. Photovoltaics (PV) convert solar energy directly into electricity. Integrating PV into buildings is now recog- nised widely as the most cost effective form of grid con- nected PV power generation (Schmela, 1999). However, for PV cells to make a major contribution to the world’s energy needs their initial cost must reduce. A solar concen- trating system is one promising approach to lower initial costs as it decreases the amount of PV required. A non- tracking concentrator is herein described, which uses novel nano-scale quantum dot technology (Feynman, 1960; Banyai and Koch, 1993; Kastner, 1993; Murray et al., 1993; Reed, 1993; Norris and Bawendi, 1995; Alivisatos, 1996; Fu and Zunger, 1996; Trindade and O’Brien, 1996; Micic et al., 1997, 1998; Peng et al., 1997; Peng and Peng, 2000) to render the concept of a fluorescent dye solar con- centrator (FSC) (Weber and Lambe, 1976; Goetzberger and Greubel, 1977; Rapp and Boling, 1978; Batchelder and Zewail, 1979; Friedman, 1981; Hermann, 1982; Filloux et al., 1983; Reisfeld and Jorgensen, 1982; Reisfeld et al., 1988; Kondepudi and Srinivasan, 1990; Soti et al., 1996; Mansour, 1997; Taleb, 2002; Earp et al., 2004) a practical proposition. A quantum dot solar concentrator (QDSC) (Barnham et al., 2000; Chatten et al., 2000; Gallagher et al., 2002, 2003; Earp et al., 2004), comprises quantum dots (QDs) seeded in materials such as plastics that are suitable for incorporation into building fac ¸ade elements with PV cells attached to the edges, converting direct and diffuse solar radiation into electricity for use in the building. A QDSC, illustrated in Fig. 1 consists of a transparent flat sheet of glass or plastic doped with QDs. Insolation incident on the surface of the concentrator is partly 0038-092X/$ - see front matter Ó 2006 Elsevier Ltd. All rights reserved. doi:10.1016/j.solener.2006.09.011 * Corresponding author. Tel.: +353 14027961; fax: +353 14027901. E-mail address: sarah.gallagher@dit.ie (S.J. Gallagher). www.elsevier.com/locate/solener Solar Energy 81 (2007) 813–821