Presentation Details
| Titanium Dioxide Mono-Material Multilayer Optical Coatings for Photovoltaics Eloy J Marcelis1, Jelle R.H.Ruiters1, Johan E.ten Elshof1, Monica Morales-Masis2. 1MESA+ Institute of Nanotechnology, University of Twente, Enschede, Netherlands.2Eindhoven University of Technology, Eindhoven, Netherlands |
Abstract
Light management via optical coatings is essential for various photovoltaic systems. Broadband anti-reflective coatings are applied to solar cells to increase power conversion efficiencies, while coatings with wavelength- and angle-selective optical properties even contribute to the development of new photovoltaic concepts. These advanced optical properties can be achieved via multilayer coatings, historically made by a combination of two different materials. This work demonstrates the design and fabrication of multilayer optical coatings formed by layers of a single material only, in this case TiO2. Refractive index contrast was achieved by combining dense and porous layers. The growth of a dense layer on top of a porous layer is challenging and typically leads to intermixing. Consequently, all reported single-material coatings that we are aware of have a step-graded structure, where each next layer has a lower density than the previous one. In this work, two novel approaches of interface engineering were explored to overcome this challenge and enable the formation of mono-material multilayer coatings with alternating dense and porous layers. The possibility of forming mono-material multilayer coatings was demonstrated by the construction of optical filters. The measured optical properties matched the designed properties, confirming successful fabrication and layer thickness control. This work demonstrates a route towards arbitrarily stacked multilayer systems that include mono-material designs and other multilayer systems involving layers with different degrees of porosity. Compared to the conventional two-material coatings, the use of a single material can lead to improved recyclability and performance, especially when using a high refractive index material like TiO2. Hence, single-material multilayer coatings can play an important role in future photovoltaic systems.
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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.