Solar power refers to the conversion of energy from sunlight into electricity. This can occur either directly using photovoltaics, indirectly using concentrated solar power, or a combination of the two approaches.
There are some downsides with solar energy. Aside from some regions of the world not receiving sufficient amounts of sunlight, there are factors of cost (especially with the initial outlay); periods of unexpectedly poor weather (cloudy and rainy days); concerns with efficiency, in terms of energy conversion; the complexities and expense of energy storage; and space issues.
Nonetheless, many researchers foresee solar power as becoming the major alternative energy source, to help humanity to achieve the necessary goals of carbon reductions, as set out in the Paris Agreement.
April 2021 has seen three innovations with solar power technology published in science journals. Each one is promising and all three have the aim of boosting solar power efficiency.
Transparent nanolayers for more solar power
Most solar cells are based on crystalline silicon. Current solar power technology delivers efficiencies of up to 23 percent. To help to raise the efficiency levels, photovoltaics researchers based at Forschungszentrum Jülich are working on a nanostructured, transparent material. This material could be fitted at the front of solar cells.
A limitation with silicon relates to the effect of recombination which takes place after the absorption of sunlight and the photovoltaic generation of electrical charge carriers. This can lead to negative and positive charge carriers combining to cancel each other out, meaning that energy is not generated.
It is hoped that the new material can counter this effect through a process described as passivation. The process begins with a thin layer of silicon dioxide, onto this a double layer of pyramid-shaped nanocrystals of silicon carbide are deposited. This occurs twice, at different temperatures. The final part involves adding a layer of indium tin oxide.
The ultra-thin layers are also transparent meaning that the incidence of light is only slightly reduced. The material also exhibits high electrical conductivity.
The research appears in the journal Nature Energy, titled “A silicon carbide-based highly transparent passivating contact for crystalline silicon solar cells approaching efficiencies of 24%.”
Carbon dots from human hair boost solar cells
Scientists have successfully used carbon dots, fashioned from human hair waste, in order to produce a type of “armor”. This protective layer is designed to improve the performance of solar technology, specifically perovskite solar cells.
The process that turns hair scraps into carbon nanodots begins by breaking down the hairs and then burning them at 240 degrees Celsius. As well as an application in solar power, the process could also be used to help to create flexible displays for smart devices.
The research shows that carbon dots form a wave-like perovskite layer where the perovskite crystals are surrounded by the carbon dots. These function to protect the perovskite material from moisture or other environmental factors. This avoids damage and thus helps to boost efficiency, in particular giving the solar cells higher power conversion efficiency and a better stability compared with perovskite cells that do not include the carbon dots.
For this technology to become commercially viable, the researchers are looking at fabrication methods to create large-scale perovskite solar panels. This includes solar cells that could be used in space missions, where the perovskite cells need to be able to cope with the extreme radiation and broad range of temperature variation in space.
The study is featured in Journal of Materials Chemistry A, where the paper is titled “Self-assembled carbon dot-wrapped perovskites enable light trapping and defect passivation for efficient and stable perovskite solar cells.”
New methodology for the reproducible fabrication of high efficiency perovskite solar cells
As the performance of perovskite photovoltaics has made solid strides in the past few years, some supporting aspects need improvement in order to help to create a more commercially viable technology.
One of the concerns is with device reproducibility. Here some solar cells have lower efficiencies than others, and the reasons for this have been difficult to disentangle.
Researchers from Technische Universität Dresden now think that the answer lies with perovskite film formation, and that this influences the reproducibility of the photovoltaic devices. In particular the duration for which the perovskite is exposed to an antisolvent appears to have a major impact on the final device performance.
The answer to improved performance lies with identifying alternative antisolvents, helping to produce a more consistent final composition. This requires the identification of key antisolvent characteristics, which the German researchers have unearthed and work is underway at developing the optimal chemicals.
The alternate apporach appears in the journal Nature Communications. The research paper is headed “A general approach to high-efficiency perovskite solar cells by any antisolvent.”
This article is part of Digital Journal’s long-running ‘Essential Science’ series where topical science stories are discussed in further detail, providing reader’s with the opportunity to understand key developments.
Last week, we learned why public health services need to plan and prepare for the possibility of the SARS-CoV-2 (coronavirus) always being an ever-present threat, endemic to most societies.
The week before the focus was with the latest research into linguistics, especially in terms of how we learn languages during our formative years. New research that considers major changes to the brain was presented.