Our big ideas, ambitious objectives and purposeful projects
Inspection of material quality and characterisation of fabrication processes across the entire production chain, from bricks and ingots to modules, are critical in improving the energy conversion efficiency of a photovoltaic system. Identifying various loss mechanisms is a key requirement to develop methods to mitigate or eliminate these losses. One of the main goals of our research group is development of novel characterisation methods for photovoltaics devices. A special focus of our group is photoluminescence-based measurement, including photoluminescence imaging, a technique that was developed at UNSW in 2005 by Professor Thorsten Trupke and Dr Robert Bardos.
In recent years, our group has expanded the applications of photoluminescence imaging, while developing new characterisation methods that are based on hyperspectral micro-photoluminescence (in the range of 4 K to 680 K!), two-photon absorption spectroscopy, and temperature-dependent measurements. We use these techniques for a wide variety of applications, including investigating the temperature coefficient of solar cells, a critical parameter that determines the performance of photovoltaic systems under real operating conditions.
Our group is also very active in the characterisation of defects in silicon wafers and solar cells. We have developed an advanced lifetime spectroscopy system based on photoconductance and photoluminescence detectors with a very wide temperature range (80 K to 680 K). This system is 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 key requirement to improve metallisation and passivation processes. Using our two-photon absorption and micro-photoluminescence spectroscopy, we deploy novel approaches to investigate defects in a wide variety of silicon ingots and wafers.
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. Results from investigations using this novel technique are expected to be published in the next few months. Beside perovskites, we have extensive experience inspecting CZTS, CIGS, CdTe, and tandem solar cells.
A few years ago, we started a new research project aiming to develop machine learning techniques for photovoltaic applications. We are using various machine learning algorithms and our extensive expertise in interpreting correlations between various metrics and solar cell performance to establish a new research area that combines photovoltaics and computer science.
Passivating contact solar cells has gained in interest immensely in the last few years. Together 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.
Recently, we have started research activities in the area of photovoltaic applications. We investigate the combination of agriculture and photovoltaic (argriPV) in Australia. We also study the use of solar cells as part of buildings (building integrated photovoltaic - BIPV) and to power the Internet of Things (IoT). A unique area of interest for us is development of high efficiency beta-voltaic devices (BV).
Our group has strong collaborations with many of the leading research groups in the world, as well as world-leading solar cell manufacturers and photovoltaic equipment and inspection companies. We regularly host world-leading scientists who join us for a few months to use our world-class systems.