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

Researchers discover regions in perovskites that could boost the efficiency of solar cells

Jun 04, 2017

A multidisciplinary team at Berkeley Lab, both from the Molecular Foundry and the Joint Center for Artificial Photosynthesis, found a possible way to dramatically boost the efficiency of methylammonium lead iodide perovskite solar cells. The team discovered a surprising characteristic of a perovskite solar cell that could be exploited for higher efficiencies, possibly up to 31%.

AFM image of low and high performing regions in perovskites

Using photoconductive atomic force microscopy with nanometer-scale resolution, the scientists mapped two properties on the active layer of the solar cell that relate to its photovoltaic efficiency. The maps revealed a bumpy surface composed of grains about 200 nanometers in length. Each grain has multi-angled facets. Unexpectedly, the scientists discovered a big difference in energy conversion efficiency between facets on individual grains. They found poorly performing facets adjacent to highly efficient facets, with some facets approaching the material’s theoretical energy conversion limit. The scientists say these top-performing facets could hold the secret to highly efficient solar cells if the material can be synthesized so that only very efficient facets develop.

NTU team printes flexible perovskite solar cells

Jun 04, 2017

A team of researchers at the Nanyang Technological University (NTU) has demonstrated a prototype of a flexible 30cm by 30cm plastic sheet with perovskite printed on it. To achieve this, various liquid chemicals, including the perovskite, are mixed together. The solution is then poured into a standard screen printer and printed onto sheets of plastic or glass.

Flexible perovskite solar cells by NTU image

The team stated that since perovskite is translucent, and its color can also be adjusted through chemical processes, perovskite solar panels could even be integrated into building facades, which is not possible with current silicon-made solar panels that are opaque and would block out light. These perovskite panels could also be cheaper to produce, costing about three times less than conventional silicon cells, the researchers said.

Ultra-stable perovskite solar cell maintains stability for over a year

Jun 04, 2017

EPFL Researchers, in collaboration with Michael Grätzel and Solaronix, have designed a low-cost and ultra-stable perovskite solar cell that has been operating at 11.2% efficiency for over a year, without loss in performance. This may represent a step towards solving the stability problem that currently poses a major obstacle towards commercialization of perovskite-based solar cell technology.

Ultra-stable perovskite solar cell remains stable for more than a year

The team engineered what is known as a 2D/3D hybrid perovskite solar cell. This combines the enhanced stability of 2D perovskites with 3D forms, which efficiently absorb light across the entire visible spectrum and transport electrical charges. In this way, the scientists were able to fabricate efficient and ultra-stable solar cells, which is a crucial step for upscaling to a commercial level. The 2D/3D perovskite yields efficiencies of 12.9% (carbon-based architecture), and 14.6% (standard mesoporous solar cells).

EPFL team develops new method to stabilize perovskite quantum dots

May 30, 2017

EPFL researchers have designed a new type of inorganic nanocomposite that makes perovskite quantum dots (nanometer-sized semiconducting materials with unique optical properties) exceptionally stable against exposure to air, sunlight, heat, and water.

Quantum dots made from perovskites have already been shown to hold potential for solar panels, LEDs and laser technologies. However, perovskite quantum dots have major issues with stability when exposed to air, heat, light, and water. The EPFL team has now succeeded in building perovskite quantum dot films with a technique that helps them overcome these weaknesses.

EPFL team develops new method to stabilize perovskite quantum dots

May 30, 2017

EPFL researchers have designed a new type of inorganic nanocomposite that makes perovskite quantum dots (nanometer-sized semiconducting materials with unique optical properties) exceptionally stable against exposure to air, sunlight, heat, and water.

EPFL team stabilizes perovskite QDs image

Quantum dots made from perovskites have already been shown to hold potential for solar panels, LEDs and laser technologies. However, perovskite quantum dots have major issues with stability when exposed to air, heat, light, and water. The EPFL team has now succeeded in building perovskite quantum dot films with a technique that helps them overcome these weaknesses.