Silicon is readily available, easy to process, highly stable and non-toxic. It is also one of the best materials for making solar cells. The high quality and purity of silicon needed for fabricating the most efficient silicon-based solar cells, however, has made it difficult to lower production costs for this renewable energy technology.
One approach that could reduce costs is to use a microscopically thin film of silicon with a textured surface to enhance light absorption. Navab Singh at the A*STAR Institute of Microelectronics and co-workers have now highlighted several key factors affecting the power conversion efficiency of surface-textured thin-film solar cells and come up with a ‘nanopillar’ design that maximizes light absorption and minimizes production costs.
The best performing thin-film silicon solar cells at present have efficiencies that are about half that of conventional bulk silicon solar cells. “By investigating a variety of appropriate vertical nanopillar designs we can enhance the light-trapping and -collection efficiency of thin films to compensate for the efficiency loss caused by reduced material quality and quantity,” says Singh.
The researchers investigated various factors that might affect the performance of a thin-film solar cell. These factors include the diameter and length of the nanopillar, as well as the spacing between nanopillars (see image). Similarly important is the design of the positively and negatively charged layers in the solar cells that are needed to separate the electrical carriers created by the absorbed light.
The researchers’ simulations showed that the thickness of the negatively charged layer on the outer side of the pillars should be as thin as possible in order to reduce ‘parasitic’ absorption—the annihilation of light-generated carriers before they cross the junction between layers where they would contribute to electrical power generation. They also found that an axial junction design in which the junction between positive and negative layers is confined to the very top of the pillars leads to a higher open-circuit voltage compared with more conventional radial junction structures in which the negative layer wraps around the entire pillars. Yet they found the converse to be true for the open-circuit current.
Singh and his co-workers therefore show that a balance of these factors is needed in order to optimize designs for light-to-power conversion efficiency in surface-textured thin-film structures, which could eventually lead to thin-film silicon solar cells that are able to match the efficiency of the more expensive single-crystalline silicon solar cells.
The A*STAR-affiliated researchers contributing to this research are from the Institute of MicroelectronicsReferences
First Juno science results supported by University of Leicester's Jupiter 'forecast'
26.05.2017 | University of Leicester
Measured for the first time: Direction of light waves changed by quantum effect
24.05.2017 | Vienna University of Technology
Staphylococcus aureus is a feared pathogen (MRSA, multi-resistant S. aureus) due to frequent resistances against many antibiotics, especially in hospital infections. Researchers at the Paul-Ehrlich-Institut have identified immunological processes that prevent a successful immune response directed against the pathogenic agent. The delivery of bacterial proteins with RNA adjuvant or messenger RNA (mRNA) into immune cells allows the re-direction of the immune response towards an active defense against S. aureus. This could be of significant importance for the development of an effective vaccine. PLOS Pathogens has published these research results online on 25 May 2017.
Staphylococcus aureus (S. aureus) is a bacterium that colonizes by far more than half of the skin and the mucosa of adults, usually without causing infections....
Physicists from the University of Würzburg are capable of generating identical looking single light particles at the push of a button. Two new studies now demonstrate the potential this method holds.
The quantum computer has fuelled the imagination of scientists for decades: It is based on fundamentally different phenomena than a conventional computer....
An international team of physicists has monitored the scattering behaviour of electrons in a non-conducting material in real-time. Their insights could be beneficial for radiotherapy.
We can refer to electrons in non-conducting materials as ‘sluggish’. Typically, they remain fixed in a location, deep inside an atomic composite. It is hence...
Two-dimensional magnetic structures are regarded as a promising material for new types of data storage, since the magnetic properties of individual molecular building blocks can be investigated and modified. For the first time, researchers have now produced a wafer-thin ferrimagnet, in which molecules with different magnetic centers arrange themselves on a gold surface to form a checkerboard pattern. Scientists at the Swiss Nanoscience Institute at the University of Basel and the Paul Scherrer Institute published their findings in the journal Nature Communications.
Ferrimagnets are composed of two centers which are magnetized at different strengths and point in opposing directions. Two-dimensional, quasi-flat ferrimagnets...
An Australian-Chinese research team has created the world's thinnest hologram, paving the way towards the integration of 3D holography into everyday...
24.05.2017 | Event News
23.05.2017 | Event News
22.05.2017 | Event News
26.05.2017 | Life Sciences
26.05.2017 | Life Sciences
26.05.2017 | Physics and Astronomy