Perovskite-Info: the perovskite experts

A team of researchers from Japan's Tokyo Tech have demonstrated perovskites' potential in the production of ammonia directly from hydrogen and nitrogen. This has the potential to open up a new approach to the manufacture of this industrially and agrochemically important gas. Ammonia is used widely an industrial reagent and in the formation of agricultural fertilizers, there are also examples of it being used as a "clean" energy carrier for hydrogen gas for fuel cells.

Masaaki Kitano and his team at Tokyo Tech point out that the main barrier to a facile synthesis of ammonia from hydrogen and nitrogen gas is the surmounting the high energy barrier needed to split diatomic nitrogen. Nitrogen-fixing plants, of course, can handle this process with a range of enzymes evolved over millions of years and metals catalysts coupled with high temperatures and pressures are the mainstays of the industrial process. There have been efforts to make perovskites in which some of their oxygen atoms have been replaced with hydrogen and nitrogen ions to act as ammonia forming materials, but these too only work at a high temperature of more than 800 degrees Celsius and the reaction takes weeks to proceed to completion. These two factors had until now meant perovskites were not looking too promising as a way to create a new ammonia process.

Researchers from Lehigh University in Pennsylvania have found that metal chalcogenide perovskites can be used as a thermoelectric material that can convert thermal energy from the sun to usable electric power.

Metal chalcogenide perovskites, with their nontoxic elemental composition, are known to offer greater thermal and aqueous stability than organic-inorganic halide perovskites. This means that they may be more suitable than other materials in the perovskite family to address the two biggest issues in commercial solar cell production: low thermal stability and toxicity.

Scientists at the National Renewable Energy Laboratory and the University of Utah have shown that the transport of electrons with a particular spin state through a two-dimensional hybrid organic-inorganic perovskite can be manipulated by introducing special organic molecules in the multilayer structure. These are chiral, which means they prefer one electron helicity over the other. The new study may advance the field of spintronics—electronics that use the minuscule magnetic fields emanating from spinning electrons as well as the electric charges of the electrons themselves—for faster, smaller electronic devices that use less energy.

The Utah researchers worked together under the umbrella of the Center for Hybrid Organic Inorganic Semiconductors for Energy (CHOISE), an Energy Frontier Research Center funded by the U.S. Department of Energy’s Office of Science, Basic Energy Sciences.

Researchers at the Georgia Institute of Technology have demonstrated a novel approach aimed at addressing perovskite’s durability problem: encasing the perovskite inside a double-layer protection system made from plastic and silica.

The research team developed a multi-step process to produce encased perovskite nanocrystals that exhibit strong resistance to degradation in moist environments.

Researchers at the Massachusetts Institute of Technology (MIT) have improved a transparent and conductive coating material by increasing its electrical conductivity by 10 times. When this coating material was integrated into a perovskite solar cell, it boosted the stability and efficiency of the solar cell.

“The goal is to find a material that is electrically conductive as well as transparent,” explained the team, which would be ‘“useful in a range of applications, including touch screens and solar cells.”

Researchers at Japan's OIST, in collaboration with the University of Pittsburgh in the U.S., have characterized the structural defects that prompt the movement of ions, destabilizing perovskite materials. The researchers' findings may help optimize perovskite solar cells.

This image of a perovskite surface shows the shifting of ions across the surface, and the vacancies causing these movements. Image by OIST

"For a long time, scientists have known structural defects exist, but didn't understand their precise chemical nature," said Collin Stecker, an OIST Ph.D. student and the first author of the study. "Our study delves into fundamental characteristics of perovskite materials to help device engineers further improve them."

An international research team that included scientists from the University of Exeter, in the U.K., Switzerland’s Ecole Polytechnique Federale de Lausanne (EPFL) and Saudi Arabia’s Center of Excellence for Advanced Materials Research has reported hitting 21.6% perovskite solar cell efficiency by using concentrator photovoltaic technology.

PSC with a concentrator

A triple-cation based, n-i-p structured perovskite cell has reportedly been developed at low levels of solar concentration. According to the researchers, standard single-junction perovskite cells usually reach efficiencies of 21% but only in devices smaller than 1mm². “The use of concentrator photovoltaics with a 0.81mm²-sized perovskite solar cell (PSC) further increased the efficiency levels up to 23.1% opening up a new line of research combining PSCs with low concentrating photovoltaic technologies,” the authors of the study wrote.