Research

The inspection of material quality and characterisation of fabrication processes across the entire production chain, from bricks and ingots to modules and systems, is critical for improving the energy conversion efficiency of a photovoltaic system. One of the main goals of our research group is the development of novel characterisation methods for photovoltaic devices, with a special focus on photoluminescence-based measurements. These include photoluminescence imaging, a technique that was developed at UNSW in 2005 by Professor Thorsten Trupke and Dr. Robert Bardos.

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In recent years, our group has expanded the applications of photoluminescence imaging and developed new characterisation methods based on hyperspectral micro-photoluminescence (in the range of 4 K to 680 K), two-photon absorption spectroscopy, and temperature-dependent measurements. We employ these techniques for a diverse range of applications, including investigating the temperature coefficient of solar cells, a critical parameter that determines the performance of photovoltaic systems under actual operating conditions.

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Our group is also highly active in characterising defects in silicon wafers and solar cells. We have developed an advanced lifetime spectroscopy system based on photoconductance and photoluminescence detectors with a very broad temperature range (80 K to 680 K). This system stands as one of the best lifetime testers in the world and allows identification of defects, even in extremely low concentration, in the bulk of silicon wafers and their surfaces. We have further developed a unique capability to measure carrier lifetime at the metal-silicon interface, a crucial requirement for improving metallisation and passivation processes. Utilising our two-photon absorption and micro-photoluminescence spectroscopy, we employ innovative approaches to investigate defects in a wide variety of silicon ingots, wafers, and cells.

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Similarly, we are very active in the characterisation of non-silicon photovoltaic materials. The first-ever luminescence images of perovskite solar cells were published by our group in 2015. Recently, we developed an injection-dependent measurement technique for perovskite semiconductors and devices. Besides perovskites, we have extensive experience inspecting CZTS, CIGS, and CdTe. Our recent project aims to develop new characterisation capabilities for tandem solar cells. Working in collaboration with our diverse industry partners, we are developing new contactless methods for indoor and outdoor inspections of various tandem structures.

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A few years ago, we initiated a new research project aimed at developing machine learning techniques for photovoltaic applications. We have developed various machine learning algorithms drawing on our extensive expertise in interpreting correlations between various metrics and solar cell performance. As one of the first groups exploring this research area, we contributed to launching a new field that combines photovoltaics and computer science. Our latest project aims to establish critical abilities for improving the operation of utility-scale photovoltaic plants as well as developing automated decision-making platforms for the end-of-life of photovoltaic systems to enhance recycling and circular economy capabilities.

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Passivating contacts for solar cells have gained immense interest in the last few years. Collaborating with our industrial partners, we are developing a novel fabrication process of transition metal oxides (TMO). It is a unique project that brings together UNSW and world-leading manufacturers of photovoltaic equipment and solar cells. Using our developed characterisation methods, we investigate the silicon-TMO interfaces and the subsequent metallisation process.

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Recently, we have commenced research activities in the area of photovoltaic applications, investigating the combination of agriculture and photovoltaics (agriPV) in Australia. Additionally, we are studying the use of solar cells in buildings (building-integrated photovoltaics - BIPV) and for powering the Internet of Things (IoT). A unique area of interest for us is the development of high-efficiency beta-voltaic devices (BV).

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Our group has strong collaborations with many leading research groups worldwide, as well as with solar cell manufacturers and photovoltaic equipment and inspection companies. We regularly host scientists who join us for a few months to utilise our world-class systems.