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Perovskite solar cell vs Silicon. The Question of Efficiency

Updated: Aug 19, 2022

Sustainability - the leader, the revolution, and the change in the scalding field of tech has been molding and marding the innovation of the new ages. The honors don't end there: sustainability is also the drive and the force combating Climate change, pollution, and global warming, you name it, leaving an ever-permanent scar on the face of innovation and tech. But on the other end of the line stands the wise old conventional resources.

As a voracious eater gobbling down tremendous chunks of resources, and environmental quality with every ounce produced, the energy of yesterday, although extensive, has lost its favor.

Having to depend on such inconsistent sources made the future of a fast-paced world running on energy seem bleak.

All that was left to lean on were the sustainable sources, which had been waiting all along to be exploited to their maximum potential.

But let's face it, the amount of energy required to run the world is not as little as one might assume, and even though depletable, the orthodox sources were up to the mark in yielding large scale while the sustainable ones were not....... there's a reason why when there's a massive solar energy spill, it's just called a 'nice day.'

Efficiency comes into the picture when what was not sufficed by quantity was met by quality.

Solar energy, insolation, and photovoltaic energy are a few terms for the most widely and efficiently used form of sustainable power.

Perovskites have demonstrated the potential to replace silicon-based traditional photovoltaic technology in this prolonged journey for better efficient solar panels or cells.

But the real question is will this so-called highly efficient material have drawbacks like silicon did, and are they worthy substitutes for a well-known element like silicon?

The current availability of solar panels can be classified into three broad categories: monocrystalline, polycrystalline and thin film. Solar power's future star material, perovskites, comes under the thin film section. Perovskite is any material that resembles the crystalline structure of calcium titanium (CaTiO3). These cells work much like an established solar cell would- a semiconductor absorbs the incident solar radiation. It initiates a flow of electrons to the opposite end by breaking the electron-hole pair, which is seized by wiring and converted into usable electricity. But what spotlights it from the rest is its high efficiency.

This potent material is relatively new to lab development but has already reached 20% efficiency and is hoped to enhance these numbers with further lab research, thereby exceeding mono- and polycrystalline cells.

Scientists all over work on higher-efficiency perovskite-based solar cells. In the U.S., Solar-Tectic LLC has produced silicon- and perovskite-based solar cells. In Neuchâtel, in Switzerland, scientists have done the same.

Perovskite solar cells harbor an advantage over traditional silicon solar cells in the simplicity of their processing. "Standard silicon cells require expensive, multistep processes conducted at high temperatures (>1000°C) in a high vacuum in special clean-room facilities. On the other hand, the organic-inorganic perovskite material can be manufactured with more straightforward wet chemistry techniques in a traditional lab environment."

Perovskite solar cells are based on an artificial material created through an approach known as "solution processing" - the same process employed while printing out newspapers, implying that the production cost will proportionally descend. On the contrary, standard photovoltaic cells must be extracted from the earth and go through a string of processes before being manipulated to devise high-quality solar cells or at least with the same quality as perovskite cells. Solution processing is given credit for improving the popularity of this material since, thanks to the cost-effectivity of this procedure, perovskites have the potential to translate the low production costs to low costs for installation, and consumers are looking to go with sustainable sources.

The solar panel is most often picturized as blue shingles on rooftops. Still, the perovskite cells can be incorporated into any part of a building besides just the roof due to their thin-film nature of flexibility, lightweight, and semi-transparency. Their lightweight nature adds to the list of advantages since it reduces the stress on structures it is incorporated with.

Like every rose has its thorn, the perovskite is not the ideal material consumers desire, although quite a long list of benefits backs it up.

Despite having the potential to replace silicon-based solar cells with low-cost fabrication and high device efficiency, perovskite solar cells also face some significant challenges. Material toxicity, device hysteresis (a lag between input and output in a system upon a change in direction), and perovskite material stability are substantial challenges that must be overpowered to be commercialized on a wide scale. The use of toxic lead in perovskite goes against the primal reasons for bringing perovskites into use. It is of the utmost demand to find a replacement for toxic lead since it eradicates the rudimentary objective of switching to sustainable sources.

Apart from toxicity, the long-term resilience of perovskite solar cells is a significant bottleneck in achieving its high potential. These high-efficiency organic-inorganic hybrid perovskite solar cells are susceptible to moisture in ambient air. Water leads to a domino effect of decomposition of perovskite film, causing material degradation, thus losing photovoltaic properties.

Temperature is also essential for perovskites, leading to decomposition at high temperatures (>90 ºC).

Such drawbacks arguably suggest that perovskites may not be the potential replacement for the long-standing, orthodox, and dependable silicon. Other than lacking efficiency, high cost of processing, and material loss, it is the protagonist in its own story. It has a few strengths to offer, like being an abundant element on the earth's surface, a non-toxic manufacturing process, and having an optimum range for photovoltaic conversion. Silicon-based solar cells now make up about 90% of the market in photovoltaic technologies.

Clearly, both have their sides of the story to narrate. To gain the best of both, another potential product that emerged from perovskite research is a combination of solar technologies called "tandem cell."

"In the space of nine years, the efficiency of these cells has risen by a factor of six. By implementing perovskite, high conversion efficiency now can be achieved at a potentially limited production cost."

In tandem cells, perovskite and silicon work hand in hand. Perovskite converts blue and green light more efficiently, while silicon converts red and infrared light better. "By combining the two materials, we can maximize the use of the solar spectrum and increase the amount of power generated. We have done the calculations, and work shows that a 30% efficiency should soon be possible," says Florent Sahli and Jérémie Werner, the leading authors of the Nature Material article.

Ultimately, the perovskite solar cells are still in progress. Still, since the silicon solar cells are approaching the limit in their conversion efficiency, the perovskite solar cells are the potential future of photovoltaic cells. So, of course, the combat does not cease here, with the perovskite cells still being nurtured and the silicon pushing boundaries for upgrades.

Whomever you may be rooting for in the fierce warfare, the primordial question still stands: will either of them be able to step toe-to-toe with the authentic antagonist, the ancestorial conventional sources?


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