Projects @ the Solar Energy Group

Projects Currently Available

A range of photovoltaic projects are currently on offer for Honours physics students. Most of the Honours projects are suitable for PhD projects. Please contact the appropriate person listed below with enquiries about these projects.

Honours Projects

The Efficiency of Photovoltaic Solar Cells at Low Temperature

Photovoltaic solar cells convert sunlight to electricity and can be understood at the most basic level as a Carnot engine, driven by the temperature difference between the sun (6000K) and the cell (~300K). In the past, extensive studies have been performed testing the performance of solar cells at elevated temperature, but none have considered the possibility of operating at a lower temperature (below 300K). The low temperature regime is interesting as the efficiency of the cell increases, due to a combination of (1) a fundamental increase in the Carnot efficiency and (2) reduction in the activity of electronic defects in the photovoltaic device. The project will involve a mixture of theory and experiment, comparing predictions of the efficiency with measurements made at different temperatures on photovoltaic devices.

Deep Level Transient Spectroscopy of Photovoltaic Semiconductors.

The power conversion efficiency of photovoltaic solar cells is highly sensitive to the presence of defects in the semiconductor material. This project applies a series of powerful techniques to analyse the nature of such defects and can be used to assess measures for overcoming their detrimental effects. In general a defect can either be a chemical contaminant and/or a structural anomaly in the crystal lattice, but in the majority of cases, the defect introduces a deep level into the semiconductor band-gap, where it serves as a centre for non-radiative recombination. When designing solar cell devices, non-radiative recombination must be minimised for efficient operation, as it is essentially a source of heat and therefore represents a loss. Recently, an advanced Deep Level Transient Spectroscopy (DLTS) system was constructed at the School of Physics. The system measures capacitance transients as a function of temperature, to determine the trapping and emission dynamics of carriers from deep-levels. Using samples supplied by leading international photovoltaic device research laboratories, the role of minority and majority carrier traps in lowering the solar cell performance will be assessed in this project. In addition, the unusual situation where a deep-level acts to enhance the photovoltaic performance of a device (impurity photovoltaic effect) can also be considered. At present, the project involves the School of Electrical and Information Engineering at the University of Sydney and several international partners located in Europe, Japan and the USA. The project offers an opportunity to explore the fundamental and practical issues that govern the effciency of photovolatic solar cells and develop a thorough understanding of semiconductor materials.

Deposition and Characterisation of Solar Selective Surfaces

Solar selective surfaces are essential to the efficient operation of solar thermal collectors. They simultaneously allow light to be efficiently absorbed whilst minimising re-emmission of heat from the solar collector due to black body radiation. Basic selective surfaces are in commercial use in plate collectors (eg Solarhart type collectors), but the current chemical-bath depositions have problems with environmental waste. Magnetron Sputtering offers a more evironmentally sustainable method of depositing solar selective surfaces, with significant reduction in waste and improved performance. The Solar Group at Sydney Uni has developed high efficiency solar selective surfaces for operation under vacuum conditions. However we are looking to expand the application of this technology to operation in air, which requires deposition, characterisation and testing of these surfaces for air conditions. The main tasks/aims/deliverables of this project are:

• Deposition of solar selective surfaces using a DC Magnetron Sputtering system.
• Performance characterisation and degradation study
  • Measurement/analysis of the optical solar selectivitity of the surface using UV-Vis-IR(-FIR) spectrophotometers and FTIR spectrometers.
  • Accelerated thermal aging of samples in air, and remeasurement of the solar selectivity to assess air stability
  • Measurement of layer variation due to thermal aging (example techniques: SNMS, SIMS, SEM - under technical supervision)
• Analysis of result to identify prime effects, potential root causes, and possible remedial solutions

Computer Modelling of Photovoltaic Concentrator Systems

Photovoltaic concentrator systems use lenses or mirrors to collect sunlight and direct it onto a small, high-performance solar cell. Predicting the electrical power output from a concentrator system is more complex than for traditional flat-plate photovoltaic panels and a detailed computer simulation was recently developed to aid the understanding of the effect of environmental parameters on the system performance. The project will involve running computer simulations to predict the performance of the world's most advanced photovoltaic concentrator system, currently being tested in Japan. Experimental data from the Japanese test site will be made available for comparison. As these concentrator systems are relatively new, the results from the project will make an important contribution towards establishing high-efficiency concentrator photovoltaic systems as a viable source of renewable energy. Additional Information: Syracuse Project Website: http://www.syracuse-pv.webhop.org

TSP Projects

The Schottky Barrier Solar Cell

The Schottky barrier solar cell represents one of the simplest designs for a photovoltaic power conversion device. It relies simply upon depositing metal onto semiconductors, but in elaborate configurations can reach power conversion efficiencies in excess of 18%. The project will involve fabricating Schottky barrier solar cells with different metals using sputter and evaporation deposition techniques. The performance of the solar cells will be assessed and correlated to the properties of the metals used to fabricate the solar cell.

Artificial Photosynthesis using Toothpaste and Blackberries - The Nanocrystalline Solar Cell:

Photosynthesis is a remarkable energy conversion process that is considerably more complex than the most sophisticated solar cell. However, the basic photosynthetic processes can be implemented in a nanocrystalline solar cell, constructed from conducting glass, titanium dioxide (toothpaste), blackberries and iodine solution. During the project a nanocrystalline solar cell will be constructed, its performance evaluated and compared to natural photosynthesis. Additional information: Sustainable Technologies International - An Australian manufacturer of Nanocrystalline 'Dye Sensitised' Solar Cells. http://www.sta.com.au/