What are perovskite?

Perovskites are a class of materials that share a similar structure, which display a myriad of exciting properties like superconductivity, magnetoresistance and more. These easily synthesized materials are considered the future of solar cells, as their distinctive structure makes them perfect for enabling low-cost, efficient photovoltaics. They are also predicted to play a role in next-gen electric vehicle batteries, sensors, lasers and much more.

How does the PV market look today?

In general, Photovoltaic (PV) technologies can be viewed as divided into two main categories: wafer-based PV (also called 1st generation PVs) and thin-film cell PVs. Traditional crystalline silicon (c-Si) cells (both single crystalline silicon and multi-crystalline silicon) and gallium arsenide (GaAs) cells belong to the wafer-based PVs, with c-Si cells dominating the current PV market (about 90% market share) and GaAs exhibiting the highest efficiency.

Perovskite solar cell market image

Thin-film cells normally absorb light more efficiently than silicon, allowing the use of extremely thin films. Cadmium telluride (CdTe) technology has been successfully commercialized, with more than 20% cell efficiency and 17.5% module efficiency record and such cells currently hold about 5% of the total market. Other commercial thin-film technologies include hydrogenated amorphous silicon (a-Si:H) and copper indium gallium (di)selenide (CIGS) cells, taking approximately 2% market share each today. Copper zinc tin sulphide technology has been under R&D for years and will probably require some time until actual commercialization.

What is a perovskite solar cell?

An emerging thin-film PV class is being formed, also called 3rd generation PVs, which refers to PVs using technologies that have the potential to overcome current efficiency and performance limits or are based on novel materials. This 3rd generation of PVs includes DSSC, organic photovoltaic (OPV), quantum dot (QD) PV and perovskite PV.

A perovskite solar cell is a type of solar cell which includes a perovskite structured compound, most commonly a hybrid organic-inorganic lead or tin halide-based material, as the light-harvesting active layer. Perovskite materials such as methylammonium lead halides are cheap to produce and relatively simple to manufacture. Perovskites possess intrinsic properties like broad absorption spectrum, fast charge separation, long transport distance of electrons and holes, long carrier separation lifetime, and more, that make them very promising materials for solid-state solar cells.

Perovskite solar cell image

Perovskite solar cells are, without a doubt, the rising star in the field of photovoltaics. They are causing excitement within the solar power industry with their ability to absorb light across almost all visible wavelengths, exceptional power conversion efficiencies already exceeding 20% in the lab, and relative ease of fabrication. Perovskite solar cells still face several challenge, but much work is put into facing them and some companies, are already talking about commercializing them in the near future.

What are the advantages of Perovskite solar cells?

Put simply, perovskite solar cells aim to increase the efficiency and lower the cost of solar energy. Perovskite PVs indeed hold promise for high efficiencies, as well as low potential material & reduced processing costs. A big advantage perovskite PVs have over conventional solar technology is that they can react to various different wavelengths of light, which lets them convert more of the sunlight that reaches them into electricity.

Moreover, they offer flexibility, semi-transparency, tailored form factors, light-weight and more. Naturally, electronics designers and researchers are certain that such characteristics will open up many more applications for solar cells.

What is holding perovskite PVs back?

Despite its great potential, perovskite solar cell technology is still in the early stages of commercialization compared with other mature solar technologies as there are a number of concerns remaining.

One problem is their overall cost (for several reasons, mainly since currently the most common electrode material in perovskite solar cells is gold), and another is that cheaper perovskite solar cells have a short lifespan. Perovskite PVs also deteriorate rapidly in the presence of moisture and the decay products attack metal electrodes. Heavy encapsulation to protect perovskite can add to the cell cost and weight. Scaling up is another issue - reported high efficiency ratings have been achieved using small cells, which is great for lab testing, but too small to be used in an actual solar panel.

A major issue is toxicity - a substance called PbI is one of the breakdown products of perovskite. This is known to be toxic and there are concerns that it may be carcinogenic (although this is still an unproven point). Also, many perovskite cells use lead, a massive pollutant. Researchers are constantly seeking substitutions, and have already made working cells using tin instead. (with efficiency at only 6%, but improvements will surely follow).

What’s next?

While major challenges indeed exist, perovskite solar cells are still touted as the PV technology of the future, and much development work and research are put into making this a reality. Scientists and companies are working towards increasing efficiency and stability, prolonging lifetime and replacing toxic materials with safer ones. Researchers are also looking at the benefits of combining perovskites with other technologies, like silicon for example, to create what is referred to as “tandem cells”.

Commercial activity in the field of perovskite PV

In September 2015, Australia-based organic PV and perovskite solar cell (PSC) developer Dyesol declared a major breakthrough in perovskite stability for solar applications. Dyesol claims to have made a significant breakthrough on small perovskite solar cells, with “meaningful numbers” of 10% efficient strip cells exhibiting less than 10% relative degradation when exposed to continuous light soaking for over 1000 hours. Dyesol was also awarded a $0.5 million grant from the Australian Renewable Energy Agency (ARENA) to commercialize an innovative, very high efficiency perovskite solar cell.

Also in 2015, Saule Technologies signed an investment deal with Hideo Sawada, a Japanese investment company. Saule aims to combine perovskite solar cells with other currently available products, and this investment agreement came only a year after the company was launched.

Latest Perovskite Solar Cell news

Perovskite solar cells gain efficiency from a glycol ether additive

Sep 19, 2017

Researchers from KAUST have found that perovskite thin films for use in solar cells are more effective when glycol ethers are added to the film-forming mix. "It yields more uniform thin films with improved structure and efficiency", explains the team.

"Our aim was to improve the quality of perovskite thin films," say the researchers. The team decided to add glycol ethers to the manufacturing process because they knew these chemicals had previously been used to help create layers of metal oxides. By trying different glycol ether mixtures and conditions the researchers eventually gained better control over the formation of their perovskite thin films, by significantly improving the structure and alignment of the perovskite grains. This increased the reproducibility and efficiency of the perovskites so that they performed more efficiently in solar cell applications. The procedure also operates at lower temperatures than alternatives, which is an important factor in improving cost effectiveness.

Saule Technologies presents breakthrough perovskite solar prototype at PSCO 2017

Sep 19, 2017

Saule Technologies has announced that it will be presenting a prototype and will answer questions regarding its flexible perovskite photovoltaic modules at the 3rd International Conference on Perovskite Solar Cells and Optoelectronics (PSCO-2017) in Oxford, UK.

Saule Technologies' flexible perovskite module image

The company will reportedly be showing an operating module printed on ultra-thin PET foil. Samples available for public viewing will present the stability of the module and underwater operation for the first time. The prototype large-scale production line capable of fabricating solar modules with a nominal power output of 100W/m2 is expected to be operational in fall of 2018.

A unique solution for optimizing perovskite materials could improve the stability of solar cells

Sep 19, 2017

A team led by scientists from the Department of Chemistry at Imperial recently studied the mechanism that causes perovskite solar cells to degrade quickly, discovering that this breakdown is due to the formation of ‘superoxides’ that attack the perovskite material. Now, the team went on to determine how the superoxides form and how they attack the perovskite material, and proposed possible solutions to the problem.

Working with researchers at the University of Bath, the team found that superoxide formation is helped by spaces in the structure of the perovskite normally taken up by molecules of iodide. Although iodide is a component of the perovskite material itself, there are defects where iodide is missing. These vacant spots are then used in the formation of superoxides.

New technique deposits high-quality large-area perovskite films with no solvents or vacuum

Sep 13, 2017

Researchers at Shanghai Jiao Tong University in China and the Swiss Federal Institute of Technology have reported the development of a new technique to deposit high-quality large-area perovskite films that does not require solvents or vacuum processing. The method reportedly produces homogeneous films with relatively few defects, which leads to an efficiency of 12.1% for a solar module made from a methylammonium lead halide film that is just over 36 cm2 in size.

Large-area perovskite films go solvent- and vacuum-free image

The research team has developed a new technique to produce large-area methylammonium lead halide (CH3NH3PbI3) perovskite films that relies on rapidly converting amine complex precursors (CH3NH3I·mCH3NH2 (where m is close to 3) and PbI2·nCH3NH2 (where n is close to 1) to perovskite films and then applying pressure to them.

Perovskite-based "solar tarps" to someday bring down costs of solar roofs

Sep 07, 2017

A team of researchers from Cambridge, MIT, Oxford, Bath and Delft universities is working on perovskite-based "solar tarp" that can be rolled onto a rooftop, instead of using rigid and heavy panels. This could, on top of other advantages, significantly bring down installation costs.

The team explains that the idea of using perovskites isn’t new, but the problem had been that tiny imperfections in the mineral’s crystal structure would trap electrons before their energy could be tapped. The team successfully tested a treatment that uses the right combination of light and humidity during the manufacturing process to “fix” the material, getting it ready for potentially years of trouble-free, ultra-efficient use.