Artificial Intelligence is helping with the development of less expensive and more efficient solar cells.
A Better Way to Make Solar Cells
Climate change is one of the most important issues affecting the modern world. In response to its impact, there is a need to switch to renewable energy sources such as solar power. Solar cells convert sunlight into electricity, providing renewable and clean energy for homes and businesses. While common solar cells are made of crystalline silicon, there is another promising material for solar cells: perovskite.
According to the U.S. Department of Energy Solar Energy Technologies Office (SETO), "Halide perovskites are a family of materials that have shown potential for high performance and low production costs in solar cells. The name “perovskite” comes from the nickname for their crystal structure, although other types of non-halide perovskites (such as oxides and nitrides) are utilized in other energy technologies, such as fuel cells and catalysts. Perovskite solar cells have shown remarkable progress in recent years with rapid increases in efficiency, from reports of about 3% in 2009 to over 25% today."
While perovskite solar cells are more efficient and cost-effective than traditional solar cells, they are also lighter and thinner, making them easier to transport and install. They are less expensive, however, optimizing the manufacturing process of perovskite cells on a large scale is difficult, due to the need to optimize about dozen or so variables simultaneously, including composition of the starting materials, temperature, humidity, processing speed, and curing methods among others. Artificial intelligence (AI) can play a vital role in speeding up the development of optimal production methods and bringing the next generation of solar power to life.
How Does a Solar Cell Work?
Solar cells, also known as photovoltaic (PV) cells, convert sunlight into electricity through a process called the photovoltaic effect. A solar cell is made up of several layers of different materials, each with a specific function. The top layer of a solar cell is typically made of a transparent material, such as glass, that allows sunlight to pass through. Beneath this layer is a thin layer of semiconducting material, typically silicon, that absorbs sunlight in order to convert it into electrical energy. This semiconducting layer is sandwiched between two electrodes, which collect the electrical current and transfer it to an external circuit.
When sunlight hits the semiconducting material, it excites the electrons and causes them to move to a higher energy level. This creates a flow of electrons, or an electrical current, between the two electrodes. This flow of electrons generates the electricity that can power devices.
Figure 1: Construction of a solar cell
Source: electricalengineering123.com
The efficiency of a solar cell refers to the percentage of sunlight that it is able to convert into electricity. The efficiency of solar cells can vary widely depending on the materials and technology used.
Challenges Faced by Silicon Solar Cell Technology
One of the challenges facing solar cell technology is energy loss. When sunlight is absorbed by the semiconducting material, some of the energy is lost as heat instead of being converted into electricity. This loss of energy can reduce the efficiency of a solar cell. Researchers are working on developing new materials and technologies that can reduce heat loss and improve the efficiency of solar cells.
Perovskite Crystals
Perovskite refers to a class of materials that have gained considerable attention in recent years for their potential applications in solar cells, LEDs, and other electronic devices. Perovskites are a group of materials with a crystal structure that is characterized by a cubic or tetragonal lattice.
The chemical composition of perovskites can vary widely, but they typically have a formula of ABX3, where A and B are cations (positively charged ions), and X is an anion (negatively charged ion). The A and B cations are typically metals, and the X anion is typically a halogen, such as iodine or bromine.
Figure 2: ABX3 Perovskite
Source: nanowerk.com
The crystal structure of perovskites is characterized by a three-dimensional arrangement of atoms that form a cage-like structure with empty spaces, or "cavities," in the lattice. These cavities can be filled with different elements or molecules, which can affect the properties of the material. The unique structure of perovskites gives them a range of interesting properties, including high conductivity, optical transparency, and the ability to absorb and emit light.
Perovskite Solar Cells
Compared to traditional silicon-based solar cells, perovskite solar cells offer several advantages. These include higher power conversion efficiencies, lower material and production costs, and greater flexibility in design and manufacturing.
Conventional solar cells are made of silicon, which can only absorb photons with energies greater than or equal to 1.1 eV. However, most sunlight reaching the Earth's surface has photon energies below this threshold, resulting in significant energy loss in the form of heat.
Perovskite solar cells, on the other hand, have bandgap energies that can be easily tuned by changing the chemical composition of the perovskite material. This makes it possible for perovskite solar cells to absorb a broader range of photons, including those with lower energies, which leads to the higher efficiency of energy conversion resulting in less heat loss.
Furthermore, perovskite solar cells can be produced using less expensive materials and manufacturing techniques, leading to lower production costs and broader adoption of solar energy.
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Challenges of Using Perovskite
Perovskite solar cells also have some drawbacks. They are less stable than silicon-based solar cells, meaning that they degrade more quickly over time when exposed to light, heat, and moisture. This can limit their lifespan and reduce their overall efficiency. Additionally, perovskites contain toxic lead, which is a concern for the environment and human health.
To address these challenges, engineers are working to develop new materials and manufacturing processes that can improve the stability and efficiency of perovskite solar cells. For example, researchers are exploring new ways to encapsulate perovskite solar cells, in order to protect them from moisture and other environmental factors. They are also experimenting with different types of materials to replace the toxic lead in perovskites.
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Solving the Challenges Using AI
Perovskite is a promising material for solar cells and other electronic devices, but it faces several challenges that need to be addressed to fully realize its potential. Artificial Intelligence (AI) can help in tackling some of these challenges, by providing data-driven insights and optimizing material properties. Here are some ways AI can solve the challenges of perovskite:
- Finding New Compositions: AI can help in predicting the properties of different perovskite compositions by analyzing the structure and electronic properties of the material, helping to find new compositions that could be less toxic and better performing. These predictive models can be based on a wide range of data, including chemical structure, toxicity data, and performance data from experiments.
- Stability and Durability: Perovskite materials are known to be unstable and prone to degradation over time, which limits their long-term applications. AI can assist in designing more stable and durable perovskite materials by analyzing the factors that contribute to their degradation and identifying possible ways to improve their resistance to environmental factors.
- Manufacturing Process: The manufacturing process for perovskite solar cells can be complex and expensive, making it difficult to scale up production. AI can help in optimizing the manufacturing process by analyzing the process parameters and identifying the optimal conditions for producing high-quality perovskite films.
- Performance Prediction: The performance of perovskite solar cells can be influenced by different factors such as composition, morphology, and processing conditions. AI can help in predicting the performance of perovskite solar cells by analyzing the relationships between these factors and the resulting device performance. This could help in identifying the optimal conditions for maximizing the efficiency of perovskite solar cells.
- Material Characterization: Understanding the physical and chemical properties of perovskite materials is essential for optimizing their performance. AI can help in analyzing and interpreting data from various characterization techniques, such as X-ray diffraction and electron microscopy, to provide insights into the structural and electronic properties of perovskite materials.
Recently, a team of researchers from MIT and Stanford University developed a system that uses machine learning to analyze raw data and measurements, as well as information based on personal observations by experienced workers. ML systems are used to analyze vast amounts of data and measurements; however, they don’t typically incorporate visual and other qualitative observations reported by researchers. Such observations often lead to the discovery of new trends, for example, overcoming challenges caused by humidity changes with temperature adjustment. The team incorporated this outside information into an ML model based on a mathematical technique called Bayesian Optimization. Because there are so many variables in the manufacturing of solar cells, evaluating all possible combinations through experimentation would be impossible, but ML is capable of identifying trends that can be used to guide the experimental process. With their ML system, the team from MIT and Stanford has already developed a manufacturing process for perovskite cells with an energy conversion efficiency of 18.5%, a competitive level for today’s market.
Summing up: Developing Perovskite Solar Cells
Silicon-based solar cells have been the most widely used technology for converting sunlight into electricity, but they suffer from energy losses due to the limitations in their efficiency and manufacturing process. However, perovskite solar cells have emerged as a promising alternative with higher efficiency and environmental benefits. Despite the potential, perovskite solar cells face several challenges, such as stability, scalability, and durability, which need to be addressed before their widespread adoption. AI can play a crucial role in addressing these challenges. With continued research and development, perovskite solar cells have the potential to revolutionize the renewable energy industry and pave the way towards a sustainable future.
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