Perovskites Solar Cells Could Replace or Enhance Silicon

According to a US Department of Energy release, when the US government allotted $128 million to improve solar power costs, a huge share of the money went to a comprehensive study of new photovoltaic materials named after Russian geologist Lev Perovski.

Projects included a $40-million research and development effort for the so-called perovskite materials, which will be used to test the adaptability and efficiency of solar cells.

Perovskites have been in existence since its discovery in 1839 in the Russian Ural Mountains. Relatively common, these materials are potentially useful to harness thousands of megawatts of the Sun's energy.

Perovskites Offer Exciting Future for Solar Cells

These perovskites are seen as providing the most exciting opportunities for solar cells in the immediate future, researchers said. Although silicon solar cells have been in use for half a century, perovskites can both improve the efficiencies of cells and directly compete with them.

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Efficiency is the main benefit of perovskites, which can be easily made into various electricity-generating materials at very low temperatures, thus would mean lower costs than silicon cells. However, the strength and stability of perovskite cells need to be addressed before they could completely replace silicon.

A report from NBC News said that scientists have found a whole new array of perovskite materials that share a particular structure, which incorporate three different chemicals in a cubic crystal shape. They identified perovskites having semiconducting power, such as silicon that is used in electronics. It was just in 2009 that scientists discovered that perovskites can be utilized in building solar cells, which transform sunlight into usable electricity.

The first perovskite cells' efficiencies were low, as such the sunlight that fell on them could not be used. But they have quickly improved. Its efficiency to convert sunlight to electrons has risen at an incredible rate, say, researchers, that even reached the levels of silicon. And because of this, they could not contain their excitement.

Reaching New Records in Conversion Efficiency

A separate study reported in Aju Business Daily showed South Korean and Swiss researchers reaching new records in achieving conversion efficiency of perovskite solar cells.

Perovskite materials are likewise made with great ease, unlike silicon which requires refinement at extreme temperatures, thus needing a great amount of energy to manufacture. Perovskites can be built into thin sheets at lower temperatures, or as inks that can be printed onto other material substrates, such as plastic rolls.

This could result in further use on surfaces wherein silicon solar cells are not practical, such as car or truck exteriors, or printed onto cloth to enable wearable electronics. Another potential use is applying thin perovskite films to the glass of windows, where sunlight goes through that can be reused for electricity.

However, the most promising application of perovskite cells is mixing them with silicon cells to use more of the Sun's energy than just merely silicon. Even the most efficient silicon cells are reaching their maximum efficiency limits of 29 percent. But perovskites cells can be adjusted to generate electricity from light wavelengths, which silicon cells don't use. Thus, covering silicon solar cells with semi-transparent films made from perovskite cells would allow it to overcome those limits.

Combined Silicon-Perovskite Cells Can Reach Beyond 50% Efficiency

Scientists see this as a combination of silicon's industrial dominance with the perovskites' technological advancement. These combined silicon-perovskite cells having efficiencies of more than 40 percent can be commercially available in 10 years, and soon be succeeded by multilayered cells with over 50 percent efficiency.

Perovskites' immense potential has been recognized by governments all over the world. It likewise provided huge opportunities for US companies as perovskites could turn into an inexpensive alternative for fossil fuels. A Physics World article revealed that perovskite fabrication techniques are in place for large-scale production.

While perovskites still have problems, such as the primary issue of stability. As they are easy to make, perovskites can degrade swiftly from heat and humidity. And while experimental perovskite cells, however, show their stability for thousands of hours, they still have a long way to go to reach the levels of stability of silicon cells, which have been used for decades.

Potential perovskite materials also use lead, which can be released into the environment, thus degrading it. Researchers are currently looking at alternatives to lead-based perovskites, such as those that are tin-based, and similar crystal structures that carry other substances.