Presentation Details
| Efficiency-Breakdown Trade-Offs in IBC Solar Cells with Embedded Bypass Diodes Paul Procel Moya, Yifeng Zhao, René van Swaaij , Olindo Isabella. TuDelft, Delft, Netherlands |
Abstract
The integration of low breakdown voltage (BDV) junctions in interdigitated back-contacted (IBC) silicon solar cells modifies local electric-field distribution and carrier transport, with direct implications on device performance. In this work, TCAD Sentaurus simulations are used to analyze IBC solar cells incorporating embedded low BDV junctions formed in the gap between highly doped p+ and n+ poly-Si carrier-selective contacts. Breakdown is governed by band-to-band tunneling (B2BT) across the gap, while forward bias operation is affected by parasitic current and recombination coupling introduced by the embedded junction. By systematically varying the gap distance and the poly-Si thickness, we reveal the dominant BDV driving mechanisms, as B2BT and current crowding can be separated and tuned through device geometry. Increasing the gap distance suppresses tunneling and increases BDV with conversion efficiency saturating beyond approximately 12 µm, whereas increasing the poly-Si thickness enhances current crowding, leading to BDV saturation above approximately 100 nm and concurrent efficiency losses. Within the investigated design space, the optimal compromise yields a conversion efficiency of 27.68 % at a BDV of -1.77 V. Overall, the results demonstrate that improving embedded bypass junctions toward lower breakdown voltage intrinsically penalizes efficiency, requiring device level optimization to balance breakdown control and photovoltaic 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.