Presentation Details
| Characterization and Modeling of 24.3% Copper Contacted n-TOPCon Solar Cell with Screen Printable Copper Pastes (yes) Ruohan Zhong1, Vijaykumar Upadhyaya1, Venkata Sai Aditya Mulkaluri1, Sagnik Dasgupta1, Wook-Jin Choi1, Young Woo Ok1, Kevin Elmer2, Ruvini Dharmadasa2, Erin Yenney2, Apolo Nambo2, Thad Druffel2, Ajeet Rohatgi1. 1Georgia Institute of Technology, ATLANTA, GA, USA.2Bert Thin Films Inc, Louisville, KY, USA |
Abstract
Silver (Ag) screen-printed metallization is the industrial standard for high-efficiency silicon solar cells, but the rapidly rising cost of Ag and increasing consumption present a challenge for long-term sustainability. This is particularly true for most promising advanced cell architectures, such as n-TOPCon that use Ag contacts on the front and back. In this work, we replaced the back Ag contacts to n-TOPCon with low-cost screen-printed Cu metallization. We demonstrate a 24.3% efficient screen-printed Cu-contacted n-TOPCon solar cell with Ag front contacts enabled with the laser-enhanced contact optimization (LECO) process. Detailed experimental characterization was performed to extract the metal-induced recombination current density (J0, metal) and contact resistivity of Ag and Cu contacts before and after LECO. The rear Cu contact on n-TOPCon exhibits a low J0, metal of 14 fA/cm², approximately four times lower than that of Ag, while achieving a post-LECO contact resistivity of 19.7 mΩ·cm². Quokka 3 device simulation was employed to simulate the fabricated solar cell efficiencies using the measured parameters. Although the higher contact resistivity of Cu requires higher rear metal coverage to minimize the series resistance, the low Cu J0, metal effectively compensates for metal-induced recombination losses. Simulation results further indicate that reducing the Cu contact resistivity to Ag would allow lower rear side metal coverage and enable n-TOPCon cell efficiencies exceeding 25% when utilizing high lifetime wafers. Additionally, 23.3% n-TOPCon solar cell with co-firing Cu paste was achieved..
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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.