Perovskite materials - Page 12

2D perovskite derivative has potential for scalable valleytronic devices

Rice University and Texas A&M University researchers have found that a 2D derivative of perovskite could make computers faster and more energy-efficient. Their material has the ability to enable the valleytronics phenomenon, which is known as a possible platform for advanced information processing and storage.

The lab of materials scientist Jun Lou of Rice's Brown School of Engineering synthesized a layered compound of cesium, bismuth and iodine that is able to store the valley states of electrons, but only in the structure's odd layers. These bits can be set with polarized light, and the even layers appear to protect the odd ones from the kind of field interference that bedevils other perovskites, according to the researchers.

Read the full story Posted: Oct 27,2020

New perovskite-based nanocatalyst shown efficient at converting greenhouse gases into hydrogen

Researchers at UNIST, POSTECH and the University of Pennsylvania have created a new perovskite-based nanocatalyst that can be used to recycle major greenhouse gases, such as methane (CH4) and carbon dioxide (CO2), into valuable hydrogen (H2) gas.

The new catalyst is hoped to promote various waste-to-energy conversion technologies, as it has over twice the conversion efficiency from CH4 to H2 than the traditional electrode catalysts.

Read the full story Posted: Oct 21,2020

NREL team develops a new wide-bandgap perovskite recombination layer called Apex Flex

Scientists at the U.S. Department of Energy’s National Renewable Energy Laboratory (NREL) have developed a new wide-bandgap perovskite layer – called Apex Flex – which they claim is able to withstand heat, light, and operational tests, and at the same time provide a reliable and high voltage.

With this material, they have built tandem solar cells with 23.1% power conversion efficiency on a rigid substrate, and 21.3% on flexible plastic. The new Apex Flex wide-bandgap perovskite recombination layer is grown with atomic layer deposition (ALD). The new material is described as a “nucleation layer consisting of an ultra-thin polymer with nucleophilic hydroxyl and amine functional groups for nucleating a conformal, low-conductivity aluminum zinc oxide layer.”

Read the full story Posted: Oct 06,2020

New production method yields flexible single-crystal perovskite films with controlled area, thickness, and composition

Scientists at UC San Diego have developed a new method to fabricate perovskites as single-crystal thin films, which are more efficient for use in solar cells and optical devices than the current state-of-the-art polycrystalline forms of the material.

Their fabrication method - which uses standard semiconductor fabrication processes - results in flexible single-crystal perovskite films with controlled area, thickness, and composition. These single-crystal films showed fewer defects, greater efficiency, and enhanced stability than their polycrystalline counterparts, which could lead to the use of perovskites in solar cells, LEDs, and photodetectors.

Read the full story Posted: Jul 31,2020

Researchers design low-temperature method for creating better perovskite crystals

Osman M. Bakr's group in the KAUST Catalysis Facility has designed a low-temperature method that can be useful for making improved single crystal perovskites. The team said that novel perovskites have positive and negative ions in the same plan as the natural perovskite calcium titanate (CaTiO3). Lead halide perovskites, having lead ions as well as halide ions, such as chlorine and iodine in the perovskite mix, are drawing attention for optoelectronic applications.

The crystals have previously been created using high temperatures, however these have created many challenges. Now, the KAUST team has developed a new approach, enabling better crystals to form.

Read the full story Posted: Jun 02,2020

Researchers develop halide double perovskite ferroelectrics

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.

Read the full story Posted: May 31,2020

Scientists develop new light-emitting material based on perovskite nanocrystals

An international team of scientists recently developed a new composite material based on perovskite nanocrystals to fabricate miniature light sources with improved performance.

Protection of perovskite nanocrystals within porous glass microspheres made it possible to increase their stability by almost 3 times. Moreover, the subsequent coating of these particles with polymers resulted in the fabrication of water-dispersible luminescent microspheres based on CsPbBr3 nanocrystals. This method of fabrication is especially important for the implementation of perovskite nanocrystals in diverse biological applications.

Read the full story Posted: May 06,2020

Researchers settle debate over Rashba Effect in perovskite materials

Scientists have theorized that organometallic halide perovskites are so promising due to a highly controversial mechanism called the Rashba effect. Scientists at the U.S. Department of Energy's Ames Laboratory have now experimentally proven the existence of the effect in bulk perovskites, using short microwave bursts of light to both produce and then record a rhythm, much like music, of the quantum coupled motion of atoms and electrons in these materials.

Research thus far hypothesized that the materials' extraordinary electronic, magnetic and optical properties are related to the Rashba effect, a mechanism that controls the magnetic and electronic structure and charge carrier lifetimes. But despite intense study and debate, conclusive evidence of Rashba effects in bulk organometallic halide perovskites, used in the most efficient perovskite solar cells, remained highly elusive.

Read the full story Posted: Apr 19,2020

X-rays reveal in situ crystal growth of lead-free perovskite solar panel materials

University of Groningen scientists are investigating in situ how lead-free perovskite crystals form and how the crystal structure affects the functioning of the solar cells, as part of their quest to find alternatives to lead-based perovskites.

The best results in solar cells have been obtained using perovskites with lead as the central cation. As this metal is toxic, tin-based alternatives have been developed, for example, formamidinium tin iodide (FASnI3). This is a promising material; however, it lacks the stability of some of the lead-based materials. Attempts have been made to mix the 3D FASnI3 crystals with layered materials, containing the organic cation phenylethylammonium (PEA). "My colleague, Professor Maria Loi, and her research team showed that adding a small amount of this PEA produces a more stable and efficient material," says Assistant Professor Giuseppe Portale.

Read the full story Posted: Apr 07,2020

Israeli researchers examine the self-healing properties of halide perovskites

Researchers at the Weizmann Institute of Science have found that in halide perovskites, creating defects takes more effort than restoring order. This finding may explain the remarkable properties of halide perovskites and help develop a new approach to controlling the properties of these and other materials.

Much about Halide perovskites still puzzles researchers; in particular, it has been unclear why they can contain relatively few defects, on the order of 1010 per cubic centimeter (that is, one defect for every trillion atoms, instead of the one to a hundred for every million, as in regular semiconductors). This concentration of defects rivals that of germanium crystals, among the cleanest solid-state man-made materials. Getting close to such a low defect concentration in the semiconductors used in today's electronic devices requires enormous effort and ingenuity. In contrast, halide perovskites can be produced within a fraction of a second by mixing simple chemical salt solutions at near room temperature.

Read the full story Posted: Sep 23,2019