Perovskite: Powering Next-Gen Solar Cells
With more than 8 billion tons of coal used every year, and over 100 million barrels of oil being consumed daily, an inevitable pressure is being put on countries to come up with efficient, renewable ways to fuel our growing society. In 2023, we saw this trend ignite, as capacity for renewable energy increased by nearly 50% globally. Now, a development in the creation of solar cells is creating a buzz in the solar energy sector. Perovskite, a highly effective synthetic semiconductor, has shown significant potential as the next material for industrial solar cell production. This article discusses the process behind this key innovation, and the potentially dramatic impact it will have on the solar power sector in the future if hurdles surrounding longevity and stability can be overcome.
The Current Picture
To understand the impact perovskite has on the solar industry, you first need to understand how solar cells work, and the impact their efficiency has on a solar panel. 95% of all industry standard solar cells are created with silicon, which is responsible for generating electricity through a phenomenon called the photovoltaic effect. This effect starts with photons from the sun striking the two silicon layers of the solar cells. One layer is coated in boron, the other in phosphorus, creating positive and negative sides which form an electron field that knocks electrons loose. This commotion of electrons is directed through the solar cells and out of a junction, forming a current. The current of electricity gets collected by metal plates on the side of the cells. Wires hooked up to the metal plates then transfer the current to inverters that convert it to functional electricity.
Despite its renewable nature, the solar cell conversion process with silicon is relatively inefficient, working at a conversion rate of only around 25%, although according to an MIT Tech Review from 2024, their theoretical maximum efficiency is around 32%. This notion of inefficiency in solar cell energy production is where the importance of the perovskite solar cells first come into play.
Perovskite Pros and Cons
The introduction of perovskite in solar cells sparked in 2009, when a Japanese scientist, Tsutomu Miyasaka, discovered it was an effective light absorber. Since then it has undergone significant testing in solar cells, and has rapidly advanced as the main option to one day replace silicon. Like silicon, perovskite undergoes the photovoltaic effect to generate energy in solar cells, but unlike silicon, perovskite is composed of a diverse range of elements with tunable properties that make it more effective. The first major differentiator of perovskite is its direct bandgap. A bandgap is defined as the distance between the valence and conduction band of electrons, and a direct bandgap means electrons do not need to pass through an intermediate state before transferring momentum. Silicon’s lack of a direct bandgap causes it to need thicker layers for light to be absorbed, creating a lower efficiency than perovskite. Furthermore, perovskite has far greater light absorption potential due to its ability to respond to a variety of colors on the solar spectrum, whereas silicon can only absorb wavelengths below or equivalent to 1,100 nm. This change highlights greater future potential for perovskite, as it could be used in solar panels capable of absorbing light from different wavelengths on the solar spectrum. Additionally, perovskite yields greater potential regarding manufacturing cost. The cost of producing perovskite is equivalent to the lowest cost of silicon, despite the many years of research which have been put into making silicon more cost-effective. Future projections show that with research, perovskite could cost a mere $0.10 per watt, “making it one of the cheapest [photovoltaic] technologies in history”. Ultimately, the greatest testament to perovskite being the more effective solar cell material is its efficiency. Since 2009, the product has jumped from 3% efficiency to nearly 30%, exceeding silicon by 5% with significantly less years of testing and research.
A table contrasting Silicon solar cells with Perovskite Solar Cells.
Though it may be more effective in many areas, perovskite is heavily outmatched in lifespan by silicon. The lifespan of the average silicon solar cell is 25 to 30 years, whereas a perovskite solar cell lasts around 2.5 years. This drastic difference in durability has caused skepticism around the implementation of perovskite solar cells on an industrial scale. Manufacturers of perovskite also face the challenge of producing large solar cells with the material, as it cannot undergo the coating process unless it is in an environment sealed off from oxygen, which decreases its performance. This hiccup in manufacturing makes coating large pieces of glass difficult, and because of this, most perovskite solar cells are still in the research stage, being coated inside of nitrogen filled boxes.
The Future of Photovoltaics
An MIT article from January outlining 10 breakthrough technologies to keep an eye on in 2024 examined the path to success for perovskite solar cells, describing it as challenging, but noting that it is gradually appearing more achievable. UK based Oxford Photovoltaic’s creation of a commercial sized perovskite tandem cell with 28.6% efficiency is the perfect testament to this. The tandem cell is far bigger than ones previously manufactured, and has the potential to be very successful if production increases in the coming year. Overall, in less time, with less research and greater challenges, perovskite solar cells have displayed higher efficiency, lower cost, and a greater light absorption potential than silicon solar cells. Perovskite solar cells, and silicon-perovskite tandem cells will certainly be something to look out for in coming years.