Physicists have discovered a novel kind of nanotube that generates current in the presence of light. Devices such as optical sensors and infrared imaging chips are likely applications, which could be useful in fields such as automated transport and astronomy. In future, if the effect can be magnified and the technology scaled up, it could lead to high-efficiency solar power devices.
Working with an international team of physicists, University of Tokyo Professor Yoshihiro Iwasa was exploring possible functions of a special semiconductor nanotube when he had a lightbulb moment. He took this proverbial lightbulb (which was in reality a laser) and shone it on the nanotube to discover something enlightening. Certain wavelengths and intensities of light induced a current in the sample—this is called the photovoltaic effect. There are several photovoltaic materials, but the nature and behavior of this nanotube is cause for excitement.
“Essentially our research material generates electricity like solar panels, but in a different way,” said Iwasa. “Together with Dr. Yijin Zhang from the Max Planck Institute for Solid State Research in Germany, we demonstrated for the first time nanomaterials could overcome an obstacle that will soon limit current solar technology. For now solar panels are as good as they can be, but our technology could improve upon that.”
Prof. Ye Jichun’s team at the Ningbo Institute of Materials Technology and Engineering (NIMTE) of the Chinese Academy of Sciences (CAS), collaborating with researchers at the University of Nottingham Ningbo China, has revealed the underlying dynamics of Silicon oxide (SiOx) tunneling junctions, including pinhole formation processes and charge-carrier transport mechanisms. The study was published in Cell Reports Physical Science.
As one of the most promising alternatives to reduce the cost and improve the efficiency of devices, tunnel oxide passivating contact (TOPCon) technology has attracted considerable attention in the photovoltaic (PV) community. However, the physical mechanism of the core structures of TOPCon, i.e., polycrystalline silicon (poly-Si)/ SiOx/ crystalline silicon (c-Si) junctions, has not been clarified, restricting the further improvement of device efficiency.
To address this problem, researchers at NIMTE conducted extensive experiments and simulations, unraveling the underlying charge carrier dynamics of the SiOx tunneling junctions.
Solar power is the third most used renewable energy source and its popularity is growing.
Determining the efficacy of organic solar cell mixtures is a time-consuming and tired practice, relying on post-manufacturing analysis to find the most effective combination of materials.
Now, an international group of researchers – from North Carolina State University in the US and Hong Kong University of Science and Technology – have developed a new quantitative approach that can identify effective mixtures quickly and before the cell goes through production.
Development of a thin-film solar cell.Image: science photo/Shutterstock
By using the solubility limit of a system as a parameter, the group looked to find the processing temperature providing the optimum performance and largest processing window for the system, said Harald Ade, co-corresponding author and Professor of Physics at NC State.
‘Forces between molecules within a solar cell’s layers govern how much they will mix – if they are very interactive they will mix but if they are repulsive they won’t,’ he said. ‘Efficient solar cells are a delicate balance. If the domains mix too much or too little, the charges can’t separate or be harvested effectively.’
‘We know that attraction and repulsion depend on temperature, much like sugar dissolving in coffee – the saturation, or maximum mixing of the sugar with the coffee, improves as the temperature increases. We figured out the saturation level of the ‘sugar in the coffee’ as a function of temperature,’ he said.
