May 2020

A research group led by Prof. Luo Junhua from Fujian Institute of Research on the Structure of Matter (FJIRSM) of the Chinese Academy of Sciences reported the first halide double perovskite ferroelectric, (n-propylammonium)₂CsAgBiBr₇, which exhibits distinct ferroelectricity with a notable saturation polarization of about 1.5 μCcm^-2.

Halide double perovskites have been found to be a promising environmentally friendly optoelectronic and photovoltaic material, exhibiting inherent thermodynamic stability, high defect tolerance and appropriate band gaps. However, no ferroelectric material based on halide double perovskites has been discovered until now.

Australian scientists have announced what could be an important step towards commercial viability of perovskite solar cells when their solar cells passed strict International Electrotechnical Commission testing standards for heat and humidity.

"Perovskites are a really promising prospect for solar energy systems," said Professor Anita Ho-Baillie, the inaugural John Hooke Chair of Nanoscience at the University of Sydney. "They are a very inexpensive, 500 times thinner than silicon and are therefore flexible and ultra-lightweight. They also have tremendous energy enabling properties and high solar conversion rates." However, unprotected perovskite cells do not have the durability of silicon-based cells, which is one of the reasons they are not yet commercially viable.

A team of researchers at The Hong Kong University of Science and Technology, the University of California, Berkeley and Lawrence Berkeley National Laboratory has built an artificial eye that uses perovskite nanowires, with capabilities that come close to those of the human eye. In their paper, the group describes developing the eye and how well it compares to its human counterpart.

The artificial eye is made with an aluminum-lined tungsten shell that serves as a round casing. It has an iris and lens in front and a retina in the back. The casing is filled with an ionic liquid. The retina has a base made of aluminum oxide dotted with pores'each of which hosts a photosensor. In the back of the retina are thin flexible wires made of a eutectic gallium'indium alloy that has been sealed using soft rubber tubes. The retina is held in place by a polymeric socket that allows for electrical contact between perovskite nanowires and the liquid-metal wires at the back. The nanowires are banded together and connect to a computer that processes light information coming from the retina.

A research team led by North Carolina State University recently reported the development of a new perovskite-based catalyst that can more efficiently convert ethane into ethylene, and could be used in a conversion process to drastically reduce ethylene production costs and cut related carbon dioxide emissions by as much as 87%.

"Our lab previously proposed a technique for converting ethane into ethylene, and this new redox catalyst makes that technique more energy efficient and less expensive, while reducing greenhouse gas emissions," says Yunfei Gao, a postdoctoral scholar at N.C. State and lead author of the new study. "Ethylene is an important feedstock for the plastics industry, among other uses, so this work could have a significant economic and environmental impact."

Australia's Monash University researchers have designed a new system incorporating 3D-printed key components, that could speed up tests on new designs for perovskite solar cells. The machine can reportedly analyze 16 sample perovskite-based solar cells simultaneously, in parallel, dramatically speeding up the process.

The invention means that the performance and commercial potential of new compounds can be very rapidly evaluated, significantly speeding up the development process. "Third generation perovskite cells have boosted performance to above 25 percent, which is almost identical to the efficiency level for conventional silicon-based ones," said project leader Adam Surmiak from the ARC Centre of Excellence in Exciton Science (Exciton Science).

A research team led by Juan Casanova and Eduard Llobet from the Departamento de Ingeniería Electrónica, Eléctrica y Automática at the Universitat Politècnica de València (URV), used graphene and perovskites to create a nanosensor that detects nitrogen dioxide with 300% improved sensitivity.

The team used graphene that is hydrophobic (water and moisture-resistant) and sensitive in gas detection, but with some limitations: it is not very selective and its sensitivity declines over time. In addition, the researchers used perovskites, a crystalline-structure material commonly used in the field of solar cells. However, they quickly deteriorate when they are exposed to the atmosphere. That's the reason why the team decided to combine perovskites with a hydrophobic material able to repel water molecules - in order to prove they can prevent or slow down their deterioration.

Two new studies have been recently released on the topic of advances in the use of plasmonic enhancement to improve performance and stability of perovskite solar cells.

In recent years, plasmonic enhancement has been used in a wide variety of research aimed at improving the efficiency and thermal stability of perovskite solar cells. The technique consists of enhancing the cells' electromagnetic field through metal nanostructures, which in turn improves the devices' low optical absorption in the visible spectrum.

Some light-emitting diodes (LEDs) created from perovskites emit light over a broad wavelength range. Scientists from the University of Groningen have now shown that in some cases, the explanation of this phenomenon is incorrect. Their new explanation should help scientists to design perovskite LEDs capable of broad-range light emission.

Wide-field photoluminescence micrographs (230_175 μm) show how somePerovskite flakes appear bright green over their entire area (left panel), whilst other flakesexhibit a distinctly red-shifted emission (right panel). Credit: University of Groningen

Low-dimensional (2D or 1D) perovskites emit light in a narrow spectral range and are therefore used to make light-emitting diodes of superior color purity. However, in some cases, researchers have noted a broad emission spectrum at energy levels below the narrow spectrum. This has attracted great interest as it could be used to produce white light LEDs more easily compared to current processes. To design perovskites for specific purposes, however, it is necessary to understand why some perovskites produce broad-spectrum emissions while others emit a narrow spectrum.

Researchers from Nigeria's African University of Science and Technology (AUST), working with scientists from Worcester Polytechnic Institute in the U.S., have suggested a novel fabrication method for perovskite solar cells.

Inspired by previous work on other organic thin-film solar cell materials, the group investigated the effects of pressure on perovskite cell production by using computational analysis and practical experimentation. A previous study at Brown University showed how the correct application of stress could heal cracks in perovskite solar cells but little information is available about how pressure could be applied to production processes.

Researchers from the University of Rome Tor Vergata, Germany's Fraunhofer Institute for Organic Electronics and the South Colombian University in Colombia have developed a flexible perovskite solar cell for indoor applications said to function under illumination of 100-500 lux.

The 100 micrometer-thick device was manufactured using roll-to-roll sputtering with an indium tin-oxide coating on ultra-thin flexible glass with transmittance of more than 80%, sheet resistance of 13 ohms-per-square and bendability surpassing 1,600 bending procedures at 20.5mm curvature.