Presentation Details
| Inter-grain Inhomogeneities Limit the Performance of CdSeTe Solar Cells Thomas Fiducia, Ian M.glass, Kara Kile, Ebin Bastola, Manoj Jamarkattel, Abasi Abudulimu, Yanfa Yan, Randy J.Ellingson, Michael J.Heben, Adam B.Phillips. University of Toledo, Toledo, OH, USA |
Abstract
CdSeTe PV modules have reached annual production volumes of over 20 GW but still have substantial VOC and fill factor (FF) deficits that limit performance. Efforts to understand the VOC and FF losses through external radiative efficiency (ERE) measurements have so far relied either on low resolution measurements or on imaging of incomplete cells that do not show the behavior of operating devices. In this work, we perform high resolution ERE imaging of a CdSeTe solar cell during operation – taking luminescence images ‘in-situ’ at multiple points along the JV curve. The measurements show that there are steep variations in ERE at the length scale of tens of µm – spanning multiple grains – that limit both Voc and FF. Following light soak, ERE becomes more homogeneous, helping to explain the performance improvements that occur following light and heat exposure. Even when high efficiency devices are imaged in the light-soaked state and at maximum power point, spots of bright luminescence remain, suggesting that removing these ‘bad diodes’ will increase the performance of high efficiency CdSeTe cells.
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No part of this publication may be reproduced, distributed, or transmitted in any form or by any means, including photocopying, recording, or other electronic or mechanical methods, without the prior written permission of the author.
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