The performance of cadmium telluride (CdTe) thin-film solar cells has improved in terms of efficiency by the addition of selenium in ground-breaking research. The blue solar panels that are on the rooftops and landscapes are made out of this semiconductor – crystalline silicon, which is also found in many electronic devices. And, over the last decade, the researchers from Colorado State University (CSU) have led pioneering studies to advance the performance and reduce the cost of solar energy. They have tried fabricating and testing new materials that usually extend beyond the capabilities of silicon. They focused on a material that has shown promise for replacing the semiconductor – it’s called cadmium telluride (CdTe).
In a key breakthrough, the researchers at CSU’s National Science Foundation in collaboration with partners at Loughborough University, United Kingdom, supported Next Generation Photovoltaics Centre and they came up with how the performance of CdTe thin-film solar cells is improved further by the addition of selenium. The result of the research was also published recently in the journal, Nature Energy. In the context, Kurt Barth, a director of the Next Generation Photovoltaics Centre and an associate research professor in the Department of Mechanical Engineering said that their paper goes right to the fundamental understanding of what happens when selenium is alloyed to CdTe.
The CSU collaborators W.S. Sampath and Amit Munshi, together with Barth and an international team could solve why the addition of selenium clocked record-breaking CdTe solar cell efficiency – the ratio of energy output to light input of over 22%. Their experiments highlighted that selenium overcomes the effects of atomic-scale defects in cadmium telluride crystals. And the results also provided a new path for widespread less expensive solar-generated electricity.
Meanwhile, the paper also highlights that electrons generated when sunlight hits the solar panel that is selenium-treated are less prone to get trapped and lost at the material’s defects, located at the boundaries between crystal grains. This increases the amount of power extracted from the solar cells. Working with materials fabricated at CSU via advanced deposition methods, the team discovered this unexpected behaviour by measuring how much light is emitted from selenium-containing panels.
In the context, Tom Fiducia, the paper’s lead author and a PhD student at the University of Loughborough, working with Professor Michael Walls stated that good solar cell material that is defect-free is very efficient at emitting light. It has also been reported that the National Science Foundation has supported the work of CSU’s Next Generation Photovoltaics Centre since 2009.