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 PV commercialization gets financial boost from the SunShot Initiative

Jul 23, 2017

Support from the US Department of Energy (DOE) will be given to several US-based development teams working to commercialize perovskite photovoltaics technology. In the latest round of funding awarded under its SunShot Initiative, the DOE will be giving $46.2 million in support of 48 different photovoltaics projects – with total funding around $65 million (when private-sector contributions are included). However, SunShot funding may be prone to changes and budget cuts proposed by the new Trump administration.

The long-term target of the funding is to achieve a levelized cost of solar-generated energy of $0.03 per kilowatt-hour (for utility-scale systems) by 2030. The SunShot initiative also has interim goals for 2020 of $0.06 per kWh for utility-scale PV, and $0.09 per kWh for residential installations. The DOE estimates the current cost of residential and utility PV at $0.18 and $0.07 per kWh respectively.

AFRL team 3D prints perovskite-based solar cells

Jul 23, 2017

The Air Force Research Laboratory (AFRL) in Ohio, USA, recently used perovskites to explore 3D printed solar cells. Using Optomec’s aerosol jet technology, the team aims to develop a more efficient and low-cost production process for harnessing solar power.

AFRL 3D prints perovskites solar cells image

The Air Force Research Laboratory is attempting to develop a manufacturing method which automates production of the solar cells to provide a viable industrial output. To do so, the team atomized perovskite materials which can be 3D printed with the Aerosol Jet technology machine. Having coated a flat surface with the droplets, the team created a solar cell with 15.4% efficiency.

Greatcell signs MOU with JinkoSolar for development of perovskite cells

Jul 22, 2017

Greatcell logo imageThe Australia-based Greatcell (formerly known as Dyesol), has signed a non-exclusive Memorandum of Understanding (MOU) with JinkoSolar, according to which the Chinese headquartered solar PV manufacturer will be given access to the company's developmental perovskite solar cells (PSC), with a long term goal to establish a formal agreement to commercialize the technology and commence large scale manufacturing.

Greatcell said that the relationship had formed over months of discussion and with the close support of Nanyang Technology University (NTU), its academic research collaboration partner in Singapore.

Microquanta reports conversion efficiency of 16% for perovskite mini-module

Jul 09, 2017

Microquanta Semiconductor logo Chinese perovskite materials startup Hangzhou Microquanta Semiconductor has reported that a 16-cm2 perovskite mini-module, certified by testing firm Newport in Montana, US has achieved a 16% conversion efficiency.

According to Microquanta, the perovskite mini-module 16% efficiency was achieved only three months after setting a prior record of 15.2%. Progress was made, primarily due to the focus on improving the deposition uniformity for large area thin films.

New printing technique yields large-grained perovskite films for improved solar cells

Jul 08, 2017

Researchers at the Georgia Institute of Technology have demonstrated that a low-temperature solution printing technique allows fabrication of high-efficiency perovskite-based solar cells with large crystals for minimizing grain boundaries. The meniscus-assisted solution printing (MASP) technique reportedly boosts power conversion efficiencies to nearly 20% by controlling crystal size and orientation.

Meniscus printing technique produces large-grained perovskite films image

The MASP process uses parallel plates (approximately 300 microns apart) to create a meniscus of ink containing the metal halide perovskite precursors. The bottom plate moves continuously, allowing solvent to evaporate at the meniscus edge to form crystalline perovskite. As the crystals form, fresh ink is drawn into the meniscus using the same physical process that forms a coffee ring on an absorbent surface such as paper. It was stated that the process could be scaled up to rapidly generate large areas of dense crystalline film on a variety of substrates, including flexible polymers.