Perovskite-Info: the perovskite experts

Researchers at Kaunas University of Technology (KTU), Lithuania, along with ones from Vilnius University and the Swiss Federal Institute of Technology, Lausanne (EPFL), have uncovered one of the possible reasons behind the short lifespan of perovskite solar cells and have offered solutions. The scientists have found that hole transporting materials used in perovskite solar cells are reacting with one of the most popular additives, tert-butylpyridine, which has a negative impact on overall device performance.

Professor Vytautas Getautis from the KTU Faculty of Chemical Technology says that so far, no attention has been paid to the possible interaction between the elements of the solar cell. For the first time, KTU chemists have uncovered the chemical reaction between the components of the hole transporting layer composition – the semiconductor and the additive used to improve the performance of the solar cell.

Two papers have recently been published, reporting on perovskite-based LEDs. The efficiencies with which some perovskite LEDs (PLEDs) produce light from electrons already seem to rival those of OLEDs.

Both papers, by Cao et al. and Lin et al., have developed PLEDs that break an important technological barrier: the external quantum efficiency (EQE) of the devices, which quantifies the number of photons produced per electron consumed, is greater than 20%. There are several similarities between the devices reported by the two groups. Perhaps most notably, the active (emissive) perovskite layer is about 200 nanometres thick in both cases, and is sandwiched between two relatively simple electrodes. This design is called a planar structure, and is the most basic manifestation of diodes made from thin films of materials. The electrodes are appropriately modified to ensure that electrons and holes (quasiparticles formed by the absence of electrons in atomic lattices) are efficiently pumped into the perovskite. As in all LEDs, when electrons meet holes, they can release energy in the form of photons through a process known as radiative recombination.

Korver Corp., an emerging solar and renewable energy company, has provided an update regarding the Company's new strategic direction in the solar energy sector. Korver has now decided to focus on its mission to develop high-efficiency commercially-manufactured Perovskite Silicon Tandem (PST) solar cells.

Mark Brown, President and CEO of Korver Corp., stated, "Our prior research has resulted in the development of highly efficient Perovskite Silicon Tandem solar cells. We plan to reach an efficiency mark of over 30% on a commercial scale by combining perovskite solar with the best silicon technologies on the market today and our own proprietary innovations. Currently, we are working towards scalability and commercial manufacturing of our PST solar cells that could change the way the world produces and consumes energy on a grand scale. We are excited to take the first mover advantage with the next big thing in solar energy."

Researchers at Pacific Northwest National Laboratory are evaluating perovskite-structured rare-earth nickelates as alternatives to replace two reactions that are considered a challenge when it comes to electrocatalysts: the oxygen reduction reaction (ORR) and the oxygen evolution reaction (OER). Both are important for the development of better fuel cells, metal-air batteries, and electrolytic water-splitting.

Materials such as platinum, iridium oxide and ruthenium oxide are well suited for these reactions, but they are scarce and expensive. The team has been working to study perovskite-structured rare-earth nickelates (RNiO₃) that can serve as bifunctional catalysts capable of performing both OER and ORR.

Researchers at Linköping University and Shenzhen University have shown how inorganic perovskites can be used to produce low-cost and efficient photodetectors that transfer both text and music. "It's a promising material for future rapid optical communication," says Feng Gao, researcher at Linköping University.

"Perovskites of inorganic materials have a huge potential to influence the development of optical communication. These materials have rapid response times, are simple to manufacture, and are extremely stable." says Feng Gao.

A next-generation optical material based on perovskite nanoparticles can achieve vivid colors even on very large screens. Due to their high color purity and low cost advantages, it has also gained much interests in industry. A recent study including researchers with UNIST has introduced a simple technique to extract the three primary colors (red, blue, green) from this material.

This innovative work was led by Professor Jin Young Kim in the School of Energy and Chemical Engineering at UNIST. In the study, the research team introduced a simple technique that freely controls light emitting spectra by adjusting the anion halides in perovskite materials. The key is to adjust the anion halides by dissolving them in solvents to achieve red, blue and green lights. Application of this technique to LEDs can result in crystal-clear picture quality.

Researchers at the Adolphe Merkle Institute in Fribourg and the Ecole Polytechnique Fédérale de Lausanne have developed a new technique to replace one of the least stable components in perovskite solar cells, which could be a major step towards commercialization.

Perovskites are seen as promising thin-film solar-cell materials because they can absorb light over a broad range of solar spectrum wavelengths thanks to their tuneable bandgaps. Charge carriers (electrons and holes) can also diffuse through them quickly and over long lengths. The most efficient perovskite solar cells usually contain bromide and MA, which is thermally unstable. To overcome this problem, researchers tried replace MA with FA since it is not only more thermally stable but also has an optimal redshifted bandgap. Unfortunately, because of its large size, FA does distort the perovskite lattice and tends to produce a photoinactive “yellow” phase at room temperature. The other photoactive “black phase” can only be seen at high temperatures. However, the researchers in this new work have now found a way to stabilize the black phase of FA at room temperature.