Presentation Details
| Revealing Dopant Metastability and Performance Limits in As-Doped CdSeTe Solar Cells via Operando X-ray Microscopy Niranjana Mohan Kumar1, Arkita Chakrabarti1, Andrew Kiss2, Arun K.M.Kanakkithodi3, Dan Mao4, Eric Colegrove5, Mariana Bertoni1. 1Arizona State University, Tempe, AZ, USA.2Brookhaven National Lab, Upton, NY, USA.3Purdue University, West Lafayette, IN, USA.4First Solar, Toledo, OH, USA.5National Lab of the Rockies, Golden, CO, USA |
Abstract
Arsenic-doped, selenium-alloyed CdTe absorbers have achieved record thin-film photovoltaic efficiencies exceeding 22%, yet device performance remains limited by competing dopant effects. While extrinsic dopants (Se, As, Cl, O) enhance carrier concentrations and lifetime, they simultaneously introduce charge compensation, sub-bandgap absorption, and interfacial defects that constrain the open-circuit voltage to below 900 mV. These defects exhibit metastable behavior under illumination, electrical bias, and thermal stress, complicating device optimization. Understanding the activation pathways of both beneficial and detrimental defects under different stressors these stressors is therefore critical. We employ correlative multimodal synchrotron X-ray microscopy—combining nano-XRF, XANES, XRD and XBIC—to probe defect activation at sub-300 nm spatial resolution. Our measurements reveal heterogeneous arsenic segregation to grain boundaries 2–3× higher than the bulk, as well as oxidation state changes following light soaking.
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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.