Research Article The Influence of Heating Time and Temperature on the Properties of CIGSSe Solar Cells Marco Giacomo Flammini, 1,2 Nicola Debernardi, 1,2 Maxime Le Ster, 2,3 Brendan Dunne, 4 Johan Bosman, 2,3 and Mirjam Theelen 1,2 1 TNO, Tin Film Technology, High Tech Campus 21, 5656 AE Eindhoven, Netherlands 2 Solliance, High Tech Campus 21, 5656 AE Eindhoven, Netherlands 3 ECN, Solar Energy, Tin Film PV Technologies, High Tech Campus 21, 5656 AE Eindhoven, Netherlands 4 NEXCIS, 190 avenue C´ elestin Coq, 13790 Rousset Cedex, France Correspondence should be addressed to Marco Giacomo Flammini; marco.fammini@hotmail.it Received 15 April 2016; Revised 16 June 2016; Accepted 12 July 2016 Academic Editor: Prakash Basnyat Copyright © 2016 Marco Giacomo Flammini et al. Tis is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. Nonencapsulated CIGSSe solar cells, with a silver grid, were exposed to diferent temperatures for various periods in order to measure the efect of the heat exposure in CIGSSe modules. Te heat treatment time and temperature were varied during the experiments, which were executed at atmospheric conditions. In all the cases, afer reaching a temperature of about 300 ∘ C, the IV measurement showed a reduction of 2-3% in terms of  OC and  SC . Tis is confrmed, respectively, by Raman and EQE measurements as well. Te efciency drop was −7%, −29%, and −48%, respectively, for 30 seconds, 300 seconds, and 600 seconds of exposure time. With temperatures larger than 225 ∘ C, the series resistance starts to increase exponentially and a secondary barrier becomes visible in the IV curve. Tis barrier prevents the extraction of electrons and consequently reducing the solar cells efciency. Lock-in thermography demonstrated the formation of shunts on the mechanical scribes only for 300 and 600 seconds exposure times. Te shunt resistance reduction is in the range of 5% for all time periods. 1. Introduction In the recent years, CIGS technology has shown notable progress in terms of performance and reliability. Te research center ZSW (Zentrum f¨ ur Sonnenenergie- und Wasserstof) has achieved the world record efciency of 21.7 ± 0.7% on a CIGS sample of 0.5 cm 2 deposited on glass substrate [1]. Tis development confrms the remarkable technological potential of thin flm technology, which could lead to a further cost reduction in the manufacturing process of solar cells. Many researchers are focusing their attention on damp degradation mechanisms involved in Cu(In,Ga)(S,Se) 2 in order to increase the lifetime and, consequently, to scale up the penetration into the market. On the other hand, less studies focus on heat treatment of the whole solar cells, which could give further information to what extend CIGS is able to withstand critical environment conditions. Ramanathan et al. [2] investigated the efect of high temperatures, and they found that CIGS samples did not show any changes in external quantum efciency (EQE) when heated up to 360 ∘ C for 30 minutes. Secondary Ion Mass Spectrometry (SIMS) results indicated that the difusion of Cadmium into the CIGS layer occurred afer heating at 400 ∘ C and concluded that the deterioration in terms of cell performance was attributable to the excess of Cd in the absorber layer and that CIGS devices are stable below 350 ∘ C. Kijima and Nakada [3] have conducted heat treatments on CIGS in air environments and have revealed signifcant changes already at a temperature of 250 ∘ C, in both the optical and electrical properties. Tey observed a reduction of the bufer layer thickness which led to an improved EQE response in the short wavelength spec- trum. Te increase in bandgap was explained by migration of sulfur, which was confrmed by SIMS measurements. Figure 1 collects literature data of nonencapsulated CIGS solar cells Hindawi Publishing Corporation International Journal of Photoenergy Volume 2016, Article ID 4089369, 7 pages http://dx.doi.org/10.1155/2016/4089369