In the 21st century, solar energy has emerged as one of the most widely embraced methods of energy production. It harnesses the radiant energy emitted by the Sun, which can then be utilised for various purposes, including generating heat, electricity, or initiating chemical reactions. Research shows that solar power will be a major source of energy by 2050.
Solar collectors, as seen in applications like solar water heating, capture solar radiation and transfer it as thermal energy to a carrier fluid, subsequently employed for heating.
Solar cells, on the other hand, directly convert solar radiation into electricity through the photovoltaic effect.
Solar energy is both boundless and environmentally friendly, though it does involve some inherent inefficiencies in the process of converting light into electricity. As the world seeks sustainable energy sources and strategies to combat human-induced global warming, solar energy is anticipated to grow in prominence, serving as a valuable tool in addressing these pressing challenges.
Perovskite solar cells are a new type of solar collectors. Comprised of differing materials and having a higher energy efficiency capacity, research shows they are a viable alternative to the more commonly used silicone solar cells.
What is Perovskite?
Halide Perovskites represent a class of materials that hold promise for achieving both high performance and cost-effective production in the realm of solar cells. The moniker “perovskite” derives from their distinctive crystal structure, although non-halide perovskite variants, such as oxides and nitrides, find applications in other energy technologies like fuel cells and catalysts. In short, perovskite is a material made up of naturally occurring minerals that are harvested and repurposed for a number of means, including solar cells.
In recent years, perovskite solar cells have exhibited remarkable improvements, experiencing rapid boosts in efficiency. Starting from reports of around 3% in 2009, their efficiency has soared to over 25% today. Despite this impressive efficiency gain in a relatively short span, several challenges must be overcome for perovskite solar cells to establish themselves as competitive commercial technology.
While perovskite solar cells have showcased competitive power conversion efficiencies (PCE) and hold potential for even greater performance, their stability falls short when compared to leading photovoltaic (PV) technologies. Perovskites are susceptible to decomposition when exposed to moisture, oxygen, extended periods of light, heat, or applied voltage. To enhance their stability, researchers are actively investigating degradation processes within both the perovskite material itself and the surrounding device layers. Enhancing the durability of these cells is of highest importance in the search for viable commercial perovskite solar products.
Challenges for Conventional Solar Cells
Currently, the vast majority of solar cells are composed of silicon. Both widely available and vastly useful, silicon itself also poses drawbacks compared to other materials, such as perovskite. Silicon solar cells, despite their many advantages, also have several disadvantages:
- Cost: The production of silicon solar cells, especially those crafted from monocrystalline or polycrystalline silicon, may entail relatively high manufacturing costs. Despite a decline in costs over time, they remain elevated compared to certain alternative technologies.
- Efficiency Limitations: Silicon solar cells are limited by an efficiency ceiling of approximately 25-27%, meaning their capacity to transform sunlight into electricity is restricted to a specific percentage. This limitation hinders their capability to generate power under low-light conditions. It also means a significant amount of energy absorbed is essentially wasted.
- Fragility: Silicon solar panels are relatively fragile and can be damaged by hail, strong winds, or physical impacts. This makes them less suitable for certain environments, elevations and terrains.
- Weight and Size: Silicon solar panels can be heavy, which can make installation more complex and costly, especially for rooftop installations. Their size and weight can also be limiting in some applications.
- Resource Intensive: The production of silicon solar cells requires a significant amount of energy and raw materials, including high-purity silicon and various chemicals. The extraction and processing of these materials can have very negative environmental impacts.
- Temperature Sensitivity: Silicon solar cells can experience a drop in efficiency as they heat up. This means that in very hot climates, their performance may be reduced.
- Energy Payback Time: The time it takes for a solar panel to generate as much energy as was used in its production can be relatively long for silicon solar cells, especially compared to some other renewable energy technologies.
Despite this, many of these disadvantages are being addressed through ongoing research and development. However, it is thought that the energy collection ceiling is one that cannot be surpassed, meaning that the advantages of traditional solar cells will never be able to outweigh the low energy efficiency. This is one of the main reasons why manufacturers and researchers are now turning to alternative materials, such as perovskite.
Benefits of Perovskite Versus Conventional Silicon Cells
Silicon serves as the predominant semiconductor material employed in the creation of solar cells and is, interestingly, the second most abundant element on Earth, trailing only behind oxygen. Solar cells can be fashioned using either amorphous or crystallised silicon. The crystallised form is the preferred and most widely used choice due to its demonstrated high power conversion efficiency (PCE). However, in order to function efficiently, the material needs to possess exceptional purity and freedom from structural imperfections, which in-turn escalates production costs.
“An advantage of perovskite is that it gives a higher voltage (over 1.9V) than silicon (~0.75V), but this comes at the cost of stability: perovskite can degrade with exposure to moisture, heat, oxygen and stress. Great efforts to improve longevity employ alternative compositions to the original, together with special contact layers and added interlayers, with the whole encapsulated against the environment.”
John – Renewable Energy Institute’s Resident Solar Photovoltaic Lecturer
The maximum attainable efficiency for silicon has plateaued at around 27%. In contrast, perovskite exhibits superior light absorption capabilities compared to crystalline silicon and can even be adjusted to harness regions of the solar spectrum that are largely inaccessible to silicon photovoltaics.
Perovskite demonstrates a unique tolerance for defects and can operate effectively even in the presence of impurities and imperfections. This remarkable material has thus piqued the interest of researchers worldwide and holds the potential to serve as a cost-effective avenue for future power generation.
This is in stark contrast to silicon photovoltaics, which require fabrication at high temperatures and under vacuum conditions, rendering them comparatively costly to manufacture. Perovskites, on the other hand, can be produced with greater ease and flexibility. Their flexibility is not just present in their manufacturing, but also in their applications – perovskites can be rolled and even printed. Compared to rigid silicon cells, which, when installed in large numbers, also occupy substantial space, perovskites provide a way to occupy less space but generate more energy.
However, perhaps a major drawback to perovskite is their tendency to produce hazardous lead compounds during the manufacturing process. As a result, scientists worldwide have been engaged in a competitive pursuit to discover alternative, more stable perovskite material. They are also exploring various strategies to enhance perovskites and their structural design in the quest to harness solar energy.
The Future of Solar Energy and Perovskite Solar Cells
Perovskite solar cells represent a photovoltaic technology with tremendous potential for integration into solar panels. They offer numerous benefits compared to conventional silicon solar cells, including cost-effectiveness, superior efficiency and increased versatility in design and manufacturing. Nevertheless, there are certain hurdles, notably concerning the long-term stability and resilience of perovskite cells. Ongoing research into perovskite solar cells is underway, with the anticipation that they will have a substantial impact on the future of solar energy.
As the world races for net zero and we are seeing the increasing fall of fossil fuel usage, the demand for the most efficient renewable energy alternative will only rise. With solar power being an endless source of energy, we can expect to see huge strides in the race for optimal solar cell deployment. Perovskite could be the future once refined, or it could be a stepping stone on the way to another miracle material that is yet to be utilised.
Whatever the future may hold for perovskite and solar cells in general, one thing is certain – the low energy efficiency of silicon solar cells mean that the use of alternative solar cell materials will inevitably become more widespread.
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