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).
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.
The latest perovskite solar news:
Oxford PV recently announced first close of Series D funding round, attracting major new investment and continued support from existing shareholders. The Company raised £31 Million - around $41 Million USD.
The round includes a major new investment from Goldwind, the leading provider of integrated renewable energy solutions in China, as well as investment from existing shareholders including Equinor and Legal & General Capital.
Researchers from Peking University have conducted an experiment which is said to have demonstrated large-area perovskite solar cells are more stable 35 km up than at ground level. The researchers tested the stability of the devices by sending them to an altitude of 35 km above the Inner Mongolia autonomous region of China using an high-altitude balloon.
The cells, which had an active area of 1 cm², were developed with a TiO2 mesoporous structure based on two mixed-cation perovskites, FA0.9Cs0.1PbI3 and FA0.81MA0.10Cs0.04PbI2.55Br0.40. “Moreover, different kinds of perovskite photoactive absorbers with and without UV filters were investigated”, the scientists said.
Korea East-West Power and Ulsan National Institute of Science and Technology (UNIST) have jointly launched a project to develop an ultra-high efficiency multi-junction solar cell using perovskite.
The company announced that researchers from the two organizations held the first meeting at its head office in Ulsan and discussed the technology of producing a standard cell (15.6×15.6 square centimeters)-sized large-scale solar panel by establishing a vacuum deposition semiconductor facility.
Researchers at the Energy Research Center of the Netherlands (ECN) have developed a bifacial tandem solar cell with a conversion efficiency of 30.2%. The new cell device – created with Dutch consortium Solliance – was made by applying a newly developed perovskite cell on top of an industrial bifacial crystalline silicon version.
This approach, according to the scientists, enables a significantly higher power conversion efficiency as one cell is optimized for high energy photons, and the other low energy particles. “The tandem device proposed here uses a four-terminal configuration, thus having separate circuits for the top and bottom cells that allow for dynamic fine tuning and optimization of the energy yield,” the creators of the cell wrote. The cell is also said to be better able to capture light on its front and rear sides by responding to the variability of incident light through its electronic design.
Researchers at the Japanese Kanazawa University aim to improve the performance of perovskite solar cells by using two kinds of titanium oxide - anatase and brookite.
The team claims to have reached a conversion efficiency of 16.82% in a perovskite cell by applying a brookite layer made of water-solute brookite nanoparticles on an anatase layer. This reportedly helps to improve the transport of electrons from the center of the cell to its electrodes, while also preventing charges from recombining at the border between the perovskite material and the electron transport layer. “Together, both these effects allow us to achieve higher solar cell efficiencies,” said the research coordinator, Md. Shahiduzzaman.