Overcoming the grain size limit to Voc in sustainable photovoltaics

Completed

Renewable Energy Sources(Solar Energy, Photovoltaics)

Basic and strategic applied research

PHYSICAL SCIENCES AND MATHEMATICS (Physics)

Not Cross-cutting

Dr K Durose
Stephenson Institute for Renewable Energy
University of Liverpool

Standard

EPSRC

01 July 2015

31 January 2019

43 months

£391,405

Energy

North West

Energy : Energy

Dr K Durose, Stephenson Institute for Renewable Energy, University of Liverpool

Solar electricity based on wafer silicon is a mature technology that is in widespread use. Although it is getting cheaper due to mass production in China, the international market is still driven by government subsidies. Alternative 'thin film' materials are the best chance of competition, but they have three problems:a) their voltages are lower than expected due to the small size of the crystal grains in them (several millionths of a meter typically),b) the materials presently used for thin film solar cells contain rare elements that will pose supply issues as the PV industry expands by several hundred fold over the next 40 years, andc) production methods must become cheaper and more effective in order to compete in the global marketWe will test a new method to make solar cells that promises to overcome all of these limitations. We will work on the archetypal earth abundant semiconductor Cu2ZnSn(S,Se)4 (CZTSS). Solar cells made from it suffer from the typical problems: It underperforms on voltage and has very small crystal grains. It is also difficult to make since it is prone to lose sulphur and selenium (the most successful research labs resort to complex methods involving nanoparticles and dangerous reducing solvents). The efficiency has been limited to 12% for some years now, and this is preventing CZTSS from becoming a production technology.In this project we will test an alternative method to grow CZTSS. We will explore the possibility of growing large grains of CZTSS on cheap metal sheet with small grains -we expect this could become a workable production route. We will make some hundreds of solar cells to test the hypotheses. Overall the idea has the potential to increase the efficiency of CZTSS from 12% to 16%, or even higher, making it feasible to open up a pathway for new PV products. A technological lead in this area could give the UK the opportunity to grab back a share of the expanding global PV business

20/07/15