Perovskite-Info: the perovskite experts

Saule Technologies has been working with construction company Skanska on integrating Saules perovskite solar cells into buildings on a commercial scale. Now, it was announced that Skanska has gone through with the installation of the first big format perovskite solar panel provided by Saule Technologies, integrated into its office in Warsaw, Poland. The size of the solar panel being tested on Skanska's Spark office building is 1.3 x 0.9 meters, containing 52 photovoltaic modules.

Skanska stated that the use of perovskite technology for zero-energy buildings is the latest innovation in the developer's sustainable building strategy. Skanska is pioneering a method of covering office building exteriors with semi-transparent perovskite solar cells on a commercial scale.

An international team of researchers, including ones from KAUST, the Guo China-US Photonics Laboratory, the University of Rochester and the University of New South Wales, has developed a technique that allows single-crystal hybrid perovskite materials to be integrated into electronics. The team stated that this achievement opens the door to new research into flexible electronics and potentially reduced manufacturing costs for electronic devices.

Challenges in integrating single-crystal hybrid perovskites into electronic devices, such as transistors, have spurred much research focus. The main challenge in incorporating single-crystal hybrid perovskites into electronics stems from the fact that these macroscopic crystals, when synthesized using conventional techniques, have rough, irregular edges. This makes it difficult to integrate with other materials in such a way that the materials make the high-quality contacts necessary in electronic devices.

A team of researchers from Kaunas University of Technology (KTU), Lithuania, along with ones from Helmholtz Zentrum Berlin (HZB) science institute, Germany, have designed a novel approach to the selective layer formation in perovskite solar cells. The molecule, synthesized by the KTU chemists, assembles itself into a monolayer, which can cover a variety of surfaces and function as a hole transporting material in a perovskite solar cell. This results in a reduction of the amount of materials used in the process, thus reducing costs.

The molecule in this work assembles itself into a monolayer and can evenly cover any oxide surface (including textured surfaces of the silicon solar cells used in tandem architectures. "It's not polymer, but smaller molecules, and the monolayer formed from them is very thin. This, and the fact that the monolayer is being formed through dipping the surface into the solution makes this method much cheaper than the existing alternatives. Also, the synthesis of our compound is a much shorter process than that of the polymer usually used in production of perovskite solar cells", says Ernestas Kasparavičius, PhD student at KTU Faculty of Chemical Technology.

The Directors of Greatcell Solar have sadly announced that a decision was taken to appoint administrators to the Greatcell Solar group of companies following sustained, but ultimately unsuccessful, attempts to secure re-financing for its activities.

Greatcell Solar Limited, Greatcell Solar Industries and Greatcell Solar Australia were placed into voluntary administration. The decision follows a series of unfortunate and unwelcome developments in recent weeks, including the untimely death of Chief Scientist, Dr Hans Desilvestro in a mountaineering accident on 10 November.

NUS scientists have found that the light emission properties of molecularly thin two-dimensional (2-D) hybrid perovskite can be tuned in a highly reversible way for ultrathin optoelectronic applications. A highly efficient photodetector has been fabricated using hybrid perovskites with the thickness of a single quantum well.

An impression of laser interaction with a molecularly thin 2D perovskites encapsulated by hexagonal boron nitride (blue layer). (Image: NUS)

Each basic unit of a 2D hybrid perovskite is constructed using a semiconducting layer of inorganic material sandwiched between two organic insulating layers. While researchers have studied layered perovskites in their bulk form for many years, the properties of these crystals when their thickness is thinned down to a few and single layers have largely not been explored.

A team of researchers from Penn State, Cornell and Argonne National Laboratory have manages to visualize, for the first time, the 3D atomic and electron density structure of the most complex perovskite crystal structure system known to date.

A reconstruction of a perovskite crystal (CaTiO3) grown on a similar perovskite substrate (NdGaO3) showing electron density and oxygen octahedral tilt. Credit: Penn State

The team explains that perovskite crystals have a distinct structure of oxygen atoms that form an octahedron — an eight-sided polygon. This arrangement of oxygen atoms acts like a cage that can hold a large number of the elemental atoms in the periodic table. Additionally, other atoms can be fixed to the corners of a cube outside of the cage at precise locations to alter the material’s properties, for instance in changing a metal into an insulator, or a non-magnet into a ferromagnet.

Researchers at the University of California, Los Angeles have used a polymer film to reduce defects in the light-absorbing perovskite, producing solar cells that are efficient and relatively robust.

The team explains that perovskites usually used in solar cells typically contain an organic cation and lead halide anions. But the heat treatment used to convert the perovskite’s precursors into a crystalline layer can also drive out some of these organic cations. This leaves defects in the material’s structure that hamper its performance and potentially make it less stable to moisture, heat, and even sunlight itself.