DoE - Page 2

A study led by scientists at the U.S. Department of Energy's (DOE) Argonne National Laboratory has shown a shape-shifting quality in perovskite oxides that could be promising for speeding up the oxygen evolution reaction (OER) that is vital for hydrogen production (and a variety of other chemical processes). The research shows that perovskite oxides could be used to design new materials for making renewable fuels and also for storing energy.

Surface evolution of a lanthanum cobalt oxide perovskite. Image credit: ANL

Perovskite oxides are less expensive than precious metals such as iridium or ruthenium that also promote OER. But perovskite oxides are not as active (in other words, efficient at accelerating the OER) as these metals, and they tend to slowly degrade.

The U.S. Department of Energy (DoE) recently announced an ambitious new target to cut the cost of solar energy by 60% within the next ten years, in addition to nearly $128 million in funding to lower costs, improve performance, and speed the deployment of solar energy technologies.

To that end, the DoE has allocated funding through its Solar Energy Technologies Office (SETO), to support advancing two materials used to make solar cells: perovskites and cadmium telluride (CdTe) thin films.

Researchers at the Department of Energy's SLAC National Accelerator Laboratory and Stanford University have used the lab's X-ray laser to watch and directly measure the formation of polarons for the first time. Polarons are fleeting distortions in a material's atomic lattice that form around a moving electron in a few trillionths of a second, then quickly disappear. Despite their transient nature, they do affect a material's behavior, and may even be the reason that solar cells made with lead hybrid perovskites achieve extraordinarily high efficiencies in the lab.

Polaron 'bubbles' of distortion form around charge carriers ' electrons and holes that have been liberated by pulses of light ' which are shown as bright spots here. Image by SLAC

Perovskite materials are famously complex and hard to understand, according to Aaron Lindenberg, an investigator with the Stanford Institute for Materials and Energy Sciences (SIMES) at SLAC and associate professor at Stanford who led the research. While scientists find them exciting because they are both efficient and easy to make, raising the possibility that they could make solar cells cheaper than today's silicon cells, they are also highly unstable, break down when exposed to air and contain lead that has to be kept out of the environment.

Researchers at the Department of Energy's Oak Ridge National Laboratory and the University of Tennessee, Knoxville, have led a study into perovskite solar cells that has revealed a way to slow phonons, the waves that transport heat.

The discovery has the potential to improve hot-carrier solar cells, which convert sunlight to electricity more efficiently than conventional solar cells by harnessing photogenerated charge carriers before they lose energy to heat.

The U.S. Department of Energy (DoE) recently announced $20 million in funding to advance perovskite photovoltaic technologies. To be competitive in the marketplace, perovskite's long-term durability must be tested and verified, which is the aim of this funding opportunity through DOE's Office of Energy Efficiency and Renewable Energy (EERE).

'Perovskites are a promising solar technology that could help us reach the next level of innovative and efficient solar power,' said Deputy Secretary of Energy Mark W. Menezes. 'Our goal is to further advance this technology here in the United States. The research and development supported by this $20 million investment will help us better understand how perovskite solar cells, which can be manufactured quickly, can further this mission.'

Scientists from Gwangju Institute of Science and Technology (South Korea), Hanwha Solution (South Korea), Korea Research Institute of Chemical Technology (South Korea), Imperial College London, Stony Brook University and U.S. Brookhaven National Laboratory have developed a new material processing protocol to boost the operational stability of planar hybrid perovskite solar cells.

A schematic showing the vacuum and solvent process for removing the ionic defects that reduce the performance of hybrid perovskite solar cells.

Typically, thin-film devices are made in solution by sandwiching the active light-absorbing material in between top and bottom metal electrical contacts (electrodes) and organic semiconductor interlayers, which enhance the extraction of electrical currents to the contacts. In this case, before putting the final electrode on top, the scientists put the device in vacuum. In prior experiments, the team had noticed that removing and then redepositing the top electrode and interlayer reduced burn-in loss, a rapid decrease in efficiency at the beginning of light illumination. They subsequently confirmed that the high-vacuum environment used to deposit the electrode had contributed to this reduction. During vacuum curing, loose ions emerge from the perovskite and concentrate at the top interlayer. In a second processing step, the scientists used a chemical solvent to selectively wash away this top layer.

The U.S. Department of Energy's (DOE's) National Renewable Energy Laboratory (NREL) has established a public-private consortium called the US-MAP for US Manufacturing of Advanced Perovskites Consortium, that aims to fast track the development of low-cost perovskite solar cells for the global marketplace.

The joint effort will aim at resolving a number of issues involving manufacturing and durability. US-MAP will also tackle sustainability issues, some of which relate to the use of lead and other metals.

Researchers at Northern Illinois University and the U.S. Department of Energy's (DOE) National Renewable Energy Laboratory (NREL) in Colorado have reported on a potential breakthrough in the development of hybrid perovskite solar cells.

Led by Tao Xu of NIU and Kai Zhu of NREL, the scientists have developed a technique to sequester the lead used to make perovskite solar cells and minimize potential toxic leakage by applying lead-absorbing films to the front and back of the solar cell.

The US Department of Energy (DOE) will allocate up to USD$125.5 million in financing for research and development (R&D) projects in the solar field. The research will target reducing the cost of solar technology, which in turn will enhance the competitiveness of the domestic photovoltaic (PV) production and improve the grid reliability.

Among other projects, the DOE funds will see USD$15 million go to 8-12 projects that aim to prolong the lifespan of PV systems and cut hardware costs for plants using traditional silicon solar cells, as well as thin-film, tandem and perovskite cells.

Researchers at the Department of Energy's SLAC National Accelerator Laboratory and Stanford University have created a nickel oxide material that shows signs of superconductivity.

Also known as a nickelate, it's the first in a potential new family of unconventional superconductors that's very similar to the copper oxides, or cuprates, whose discovery in 1986 raised hopes that superconductors could someday operate at close to room temperature and revolutionize electronic devices, power transmission and other technologies. Those similarities make scientists wonder if nickelates could also superconduct at relatively high temperatures.