Presentation Details
| Initiation of the CdCl2 activation process for CdSeTe/CdTe photovoltaic devices Kieran M.Curson1, Pascal Jundt2, Bettina Spaeth2, Christian Drost2, Robert Arndt2, John M.Walls1. 1Loughborough University, loughbrough, United Kingdom.2CTF Solar GmbH, Dresden, Germany |
Abstract
CdCl2 activation is essential for high efficiency CdSeTe/CdTe solar cells, yet the early stages of the process are not fully understood. Here, we track the structural, compositional, and device-level evolution of CdSeTe/CdTe devices during CdCl2 treatment at 420 °C as a function of time. Device performance improves with activation time, reaching an optimum at ≃40 min, with under- and over-treatment leading to performance losses. Microscopy reveals that chlorine rapidly migrates to the front interface within the first minute, primarily along grain boundaries, initiating defect passivation. Selenium diffusion follows, first along grain boundaries and then into grain interiors, driving the formation of a graded CdSeTe alloy and removal of residual CdSe within ≃10 min. Tellurium exhibits a similar transport pathway, migrating along grain boundaries toward the front interface before diffusing into grain interiors, with undertreated devices retaining a CdTe-rich interfacial phase. These processes are accompanied by grain growth, stacking fault reduction, and texture randomization. Together, the results show how chlorine- assisted defect passivation and selenium redistribution during CdCl2 activation leads to optimized device performance.
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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.