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Dr John D. Murphy

Silicon materials for high efficiency photovoltaic solar cells

Photovoltaics have the potential to supply the majority of the world’s electricity. Today’s market is dominated from cells made from bulk silicon (~90%) and silicon’s abundance and properties (chemical stability, density, band gap, and non-toxicity) mean that there is a good chance it will continue to dominate in the longer term. Although uptake of photovoltaic technologies is increasing rapidly, without subsidy all stable photovoltaic technologies are too expensive to compete with incumbent electricity generation sources. Academic research is needed to improve the performance of materials to produce more cost-effective silicon solar cells.

The performance of the very highest efficiency silicon solar cells (e.g. back-junction back-contact cells) is becoming limited by the minority carrier lifetime in the substrate. Although carrier lifetimes in the best silicon wafers now routinely exceed 1ms, the best cells will soon require lifetimes of > 10ms. Although in normal operating conditions such lifetimes are physically possible, defects in the material mean that they are seldom achieved in practice. Recombination centres present in very low concentrations (parts in a million million) can impinge on the carrier lifetime. This project aims to understand the origin of this weak recombination activity, and ideally developing ways to overcome it. Experimental techniques such as photoconductance lifetime measurements and photoluminescence imaging will be used, and there will be a need for occasional cleanroom working. The project will be in collaboration with a leading silicon manufacturer.

This PhD project requires prior knowledge and an interest in semiconductor materials. It would ideally suit a candidate with an undergraduate degree in physics, materials science, or electrical engineering. Informal enquiries can be made to Dr Murphy by e-mail ( Please attach a CV.

Note: Should your application for admission be accepted you should be aware that this does not constitute an offer of financial support. Please refer to the scholarships & funding pages.