A new “wonder material” is reshaping the solar cell industry. After only seven years of development, peroskovite-based solar cells have attained the same power efficiency as its long standing silicon-based cousin. The new liquid compound is cheaper to produce, more flexible to use, and better for the environment. While there are still a few hurdles left, the world could be on the brink of an energy revolution.

What is peroskovite?

Persoskovite is a broad class of materials that join carbon with organic molecules (like hydrogen) to form a three-dimensional crystal structure that is bound to a metal (like lead) and a halogen (like chlorine). That sounds pretty complicated – and it is. More important to understand than the actual chemistry and physics involved is how this compares to silicon-based solar cells.

Both peroskovites and silicon-based photovoltaic cells have the ability to capture light energy and turn it into electricity. From a physical viewpoint, the major difference is that peroskovite is made through a relatively simple chemical combination and results in an adhesive liquid. The process is much simpler than the multi-step silicon process that includes specialized high-heat, electrode-arc furnaces and creates hard, inflexible power cells.  

Further, peroskovites form naturally and have a wide range of base elements enabling a wide range of experimentation and improvement as a solar cell. A key component considering the compound was only first researched for solar energy 7 years ago.

Peroskovite has huge power potential

In 2009, peroskovite solar cells were first introduced with a meager power efficiency of 3.8 percent. This was a far cry from silicon photovoltaic cells’ 25% efficiency. In 2012, a breakthrough in peroskovites set off a rapid increase in efficiency. By 2014, peroskovite cells were regularly recording 20% efficiencies. And in April of this year, the Hong Kong Polytechnic University announced they had created a peroskovite solar cell with a 25% efficiency.

By comparison, silicon-based cells have been stagnating in efficiencies for the last two to three decades.

Image: National Renewable Energy Laboratory

The theoretical efficiency of silicon solar cells has increased to nearly 50% in some models but the actual efficiency of installed cells has plateaued. The reasons are debated but one agreed upon barrier for silicon solar cells is their inflexibility.

Flexibility of use

Silicon solar cells need large flat surfaces to perform well. In theory, perovskite solar cells (or more accurately the liquid solution that hardens and conducts electricity) could be adhered to any surface including shingles or exterior surfaces of even highly irregular shaped buildings.

The inflexibility of silicon solar cells has been an inherent ceiling in efficiency and use. Peroskovites would leap frog silicon on both. The adhering liquid nature of the peroskovite solution could also gain solar energy the customers who have been put off by the visual of large rigid solar panels sticking up from their roof or front yards.

Production costs

Second only to the power efficiency improvement, the potential for lower production costs is the most attractive feature of peroskovites. The one step process to creating perovskite solar cells is significantly simpler and cheaper than the silicon based solar cells. By some estimates, the cost of a perovskite solar cell would be one fourth the cost of a silicon cell.  A substantial improvement in an industry where silicon cells have plateaued at about 80 cents a cell.

Better for the environment

Solar cells are already a positive for the environment when they replace burning fossil fuels. Perovskite has the potential to go even farther by eliminating the release of carbon dioxide during silicon cell creation. The current process to create silicon based solar cells requires melting silicon dioxide in a furnace at temperatures between 1,500 and 2,000 degrees Celsius. Perovskite’s simpler chemical reaction based creation process avoids this carbon emitting step.

Works better at higher temperatures

A new study shows that peroskovites’ peak efficiency occurs at 57 degrees. A study by Wei Lin Leong of Singapore’s Agency for Science, Technology, and Research in the Advanced Materials journal shows peroskovites work substantially better at higher temperatures than silicon based solar cells. Considering most regularly sunny areas are in hotter climates, this would give peroskovite a substantial advantage over silicon cells in the places they are most likely to be used.

The one major downside

Ok, so it can’t all be sunshine and happiness. Peroskovites have a serious durability problem. The peroskovite chemical solution can degrade, even in a matter of days, in moist environments. Early experimentation has combined other chemicals into the liquid compound that can extend the lifespan of the peroskovite solar cells. Despite improvements, more research will be required to fix this troubling concern.

This problem may not be as insurmountable as it seems on its surface. Today, Physics.org published findings that hybrid peroskovites can solve many of the new materials problems, particularly its current reliance on toxic lead and the durability issue. These findings are still preliminary (some are based on computer modeling rather than hands on experimentation) but a promising sign of near future development.

The future is sunny

“This new class of solar cell is only around four years old, so although it has high performance, people don’t understand the system and why it’s doing so well,” Wei Lin Leong told the Indian Express.

Given the relatively short time spent developing peroskovite solar cells, it’s exciting to consider the potential improvements in just the next few years.

Already some solar startups are promising peroskovite based solar cells in 2017. It seems the next big thing in solar is already here.


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