Researchers create a perovskite-based nickel oxide material that shows signs of superconductivity

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.

ANU team announces 21.6% efficiency for their perovskite solar cells

Researchers from the Australian National University (ANU) have reportedly broken new ground in solar cell energy efficiency and in the process provided a glimpse of the technology’s future. The researchers have a announced a record of 21.6% efficiency, which they say is the highest achieved for perovskite cells above a certain size.

Associate Professor Thomas White says as a comparison, typical solar panels being installed on rooftops right now have efficiencies of 17-18%. “There are three things you’re trying to achieve with solar cells, you’re trying to make them efficient, stable and cheap," he said. "Perovskites are the future of solar cells."

KAUST team finds that small changes may cause big improvements in perovskite solar cells

Researchers from the KAUST Solar Center have monitored the impact of compositional changes on the structural organization and photovoltaic properties of perovskite thin films in situ. The team has reached a conclusion that may benefit perovskite solar cells in the future - that changes in composition affect light-harvesting layer crystallization and perovskite solar cell efficiency.

Sequence of fabrication of a perovskite thin film from precursor solution to solid filmimageSequence of fabrication of a perovskite thin film from precursor solution to solid film via the spin-coating deposition process. Image by KAUST

Solar cell performance and stability depend on the morphology of the thin films, especially their ability to crystallize in the so-called photoactive α-phase. Perovskites that contain lead tend to combine various halides, such as the anionic forms of bromine and iodine, with mixtures of methylammonium, formamidinium, cesium and other cations. These have led to record conversion efficiencies and thermal stabilities compared with their single-halide, single-cation analogs. However, these mixed-halide, mixed-cation perovskite films have been characterized only through ex-situ postdeposition techniques. This limits the understanding of the mechanisms that govern their growth from their sol-gel precursor to their solid state and stalls attempts to improve device performance and stability.

New method quantifies the efficiency of crystal semiconductors

Researchers at Tohoku University in Japan have found a new way to successfully detect the efficiency of crystal semiconductors. For the first time, the team used a specific kind of photoluminescence spectroscopy, a way to detect light, to characterize the semiconductors. The emitted light energy was used as an indicator of the crystal's quality. This method will potentially yield more efficient light-emitting diodes (LEDs), solar cells and several other advances in electronics.

Internal quantum efficiency of semiconducting crystals quantified by new method imageSchematic of the ARPL measurement technique

"For further development of perovskite-based devices, it is essential to quantitatively evaluate the absolute efficiency in high-quality perovskite crystals without assuming any predefined physical model is of particular importance," said corresponding author Kazunobu Kojima, Associate Professor at Tohoku University, Japan. "Our method is new and unique because previous methods have relied on efficiency estimation by model-dependent analyses of photoluminescence."

Mixing perovskite nanoparticles with 2D perovskites may give a boost to the efficiency of blue LEDs

Researchers from Zhejiang University, the Beijing Institute of Technology and Nanjing Tech University in China, Argonne National Laboratory in the U.S, University of Cambridge in the UK have combined perovskite nanoparticles with 2D perovskites to double the efficiency of blue LEDs.

Perovskite particle mix to push forward blue LEDs imageBromide perovskite films consisting of nanoparticles embedded within 2-D perovskite layers produce blue LEDs with a record-high efficiency of 9.5%

While the device only glows for a few minutes, the work is still considered “a big step toward the development of high-performance blue perovskite emitters” says Jianjun Tian of the University of Science and Technology in Beijing, who was not involved in the work. “The efficiency of these blue perovskite LEDs is already higher than that of the commercially available blue organic LEDs.”