Towards highly efficient thin-film solar cells with a graded-bandgap CZ TSSe layer. Part II: Piecewise-homogeneous bandgap grading
Date
2024-11-14
Journal Title
Journal ISSN
Volume Title
Publisher
JPhys Energy
Abstract
In Part I, we optoelectronically optimized a thin-film solar cell with a graded-bandgap CZTSSe photon-absorbing layer and a periodically corrugated backreflector, using the hybridizable discontinuous Galerkin (HDG) scheme to solve the drift-diffusion equations. The efficiency increase due to periodic corrugation was minimal, but significant improvement was achieved with a nonlinearly graded bandgap. Due to occasional failures of the HDG scheme from negative carrier densities, we developed a new computational scheme using the finite-difference method, which also reduced the overall computational cost of optimization. Later, a normalization error was discovered in the electrical submodel in Part I, but it did not alter the overall conclusions. We have now re-optimized the solar cells with (i) a homogeneous bandgap, (ii) a linearly graded bandgap, or (iii) a nonlinearly graded bandgap, and (iv) a piecewise-homogeneous bandgap which is easier to implement than a continuously graded bandgap. An efficiency of 13.53% is predicted with a three-layered piecewise-homogeneous CZTSSe layer. Furthermore, concentrating sunlight by a factor of one hundred can boost the efficiency to 16.70% with the piecewise-homogeneous bandgap.
Description
This article was originally published in JPhys Energy. The version of record is available at: https://doi.org/10.1088/2515-7655/ad8ef4.
© 2024 The Author(s). Published by IOP Publishing Ltd.
Original content from this work may be used under the terms of the Creative Commons Attribution 4.0 license (https://creativecommons.org/licenses/by/4.0/). Any further distribution of this work must maintain attribution to the author(s) and the title of the work, journal citation and DOI.
Keywords
bandgap grading, optoelectronic optimization, thin-film solar cell, earth-abundant materials, CZTSSe solar cell, affordable and clean energy, industry, innovation and infrastructure
Citation
Ahmad, Faiz, Peter B Monk, and Akhlesh Lakhtakia. “Towards Highly Efficient Thin-Film Solar Cells with a Graded-Bandgap CZ TSSe Layer. Part II: Piecewise-Homogeneous Bandgap Grading.” Journal of Physics: Energy 7, no. 1 (January 31, 2025): 015002. https://doi.org/10.1088/2515-7655/ad8ef4.