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The University of Southampton
University of Southampton Malaysia

University of Southampton to develop highly efficient solar cell solutions

Published: 16 March 2018
Dr Stuart Boden
Dr Stuart Boden teaches semiconductor devices on several UG and MSc modules at Southampton

A new approach, inspired by the special patterns found on moth eyes, is being applied to mono- and multi-crystalline silicon, which could lead to remarkably reflection-free and highly efficient solar cells.

A team of researchers including Southampton Malaysia’s flying faculty Dr Stuart Boden, is investigating a new method of texturing the top surface of solar cells that improves light absorption without compromising electrical performance.

‘‘Solar cells are a great source of clean electrical energy but reducing the ratio of the cost to the energy generated over their lifetime is essential for continuing their wide-spread deployment. One way to do this is to generate more energy by reducing the amount of light lost due to reflection’’ says Dr Boden.

The team’s new method draws inspiration from moth eyes, which are black due to being covered in tiny posts.

‘’Each post is smaller than the wavelength of light and when light hits the moth’s eye, much of it gets absorbed into its cornea without disruption. This is what our team is trying to replicate in silicon but using techniques that are compatible with low-cost, large-scale manufacturing, ’’ explains Dr Boden, co-investigator on this EPSRC-funded project.

Today, silicon solar cell makers commonly use a thin film coating on a surface textured with micron-scale features to reduce reflection losses. The team believes that a combination of micron and nano-scale texturing, achieved with potassium hydroxide (KOH) and metal assisted chemical etching (MACE) on monocrystalline silicon, could reduce reflectance losses further- creating so called “black” silicon.

Dr Boden explains that the key to translating a decrease in reflectance to an increase in power conversion efficiency is the subsequent treatment of the surface to mitigate any electrical degradation due to the texturing. It is also important to consider how these surfaces perform when the solar cell is enclosed in plastics and glass to form a module.

In addition to this, the research team will develop new processes for multi-crystalline silicon based on ozone/HF gas-phase processing which is compatible with modern diamond wire saw techniques used for slicing silicon into wafers.

‘’This exciting new phase of collaboration with Oxford University will put the next generation of solar cell production on more cost-effective foundations through robust design methods for surface texturing. This will be challenging but important if solar cell production and deployment is to continue to be scaled up,’’ says Dr Boden.

The Black Silicon Photovoltaics project is funded by the EPSRC (Engineering and Physical Sciences Research Council). Dr Boden collaborates with fellow researchers from University of Southampton and University of Oxford and industrial consultants from Tetreon Technologies and Trina Solar. Research institutes at Fraunhofer ISE, Germany and UNSW, Australia are also involved in the project.

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