Perovskite materials - Page 10

A research team at HZB has used four-dimensional modelling to interpret structural data of methylammonium lead bromide (MAPbBr₃), identifying incommensurable superstructures and modulations of the predominant structure.

Despite intensive research, it was not possible to precisely elucidate the crystal structures of perovskites with their diverse modulations and superstructures as a function of temperature, even for the best-known perovskite compounds such as methylammonium and formamidinium lead halide. Now, the HZB team has analyzed structural data of methylammonium lead bromide (MAPbBr₃) with a novel model. Postdoc Dr. Dennis Wiedemann used a model that takes a fourth dimension into account in addition to the three spatial dimensions. The structural data were measured at a temperature of 150 Kelvin at the University of Columbia.

Researchers at Duke University have revealed the illusive molecular dynamics that provide halide perovskites with their desirable properties for solar energy and heat energy applications.

A key contributor to how these materials create and transport electricity reportedly stems from the way their atomic lattice twists and turns in a hinge-like fashion. The results could help materials scientists tailor the chemical recipes of these materials for a wide range of applications in an environmentally friendly way.

Researchers from Clemson University, Los Alamos National Laboratory, Huazhong University of Science and Technology, Jilin University, Kowloon Tong Hong Kong, the Israeli Technion and The University of Alabama have used laser spectroscopy in a photophysics experiment, and have broken new ground that could result in faster and cheaper energy to power electronics.

This novel approach, using solution-processed perovskites, could revolutionize a variety of everyday objects such as solar cells, LEDs, photodetectors for smart phones and computer chips. The goal of the research was to make materials that are more efficient, cheaper and easier to produce.

Researchers at the Department of Energy's Oak Ridge National Laboratory (ORNL) and the University of Tennessee have proposed a way to automate the search for new materials, with a focus on metal halide perovskites (MHPs), to advance solar energy technologies. The study, part of an ORNL-UT Science Alliance collaboration, aims to identify the most stable MHP materials for device integration.

The automated workflow combines chemical robotics and machine learning to speed the search for stable perovskites. Credit: Jaimee Janiga/ORNL, U.S. Dept of Energy

The team has developed a novel workflow that combines robotics and machine learning to study metal halide perovskites. 'Our approach speeds exploration of perovskite materials, making it exponentially faster to synthesize and characterize many material compositions at once and identify areas of interest,' said ORNL's Sergei Kalinin.

Scientists in Italy have devised a way to fine-tune the optical emission and robustness of a new set of Ruddlesden'Popper metal'halide layered perovskites. It is shown that the type of molecule regulates the number of hydrogen bonds that it forms with the edge'sharing [PbBr₆]^4' octahedra layers, leading to strong differences in the material emission and tunability of the color coordinates, from deep'blue to pure'white. In addition, the emission intensity strongly depends on the length of the molecules, thereby providing an additional parameter to optimize their emission efficiency.

The combined experimental and computational study provides a detailed understanding of the impact of lattice distortions, compositional defects, and the anisotropic crystal structure on the emission of such layered materials.

Five Wrocław University of Science and Technology researchers have been awarded over than 12 million PLN (around USD$3.2 million) for research projects under the Maestro and Sonata Bis competitions organized by the National Centre for Science. Among the research area are perovskites, active enzymes, and artificial intelligence.

Targeting experienced scientists, Maestro is a competition for research projects aimed at carrying out pioneering, and also interdisciplinary, research that is important for the development of science and reaching beyond the current state of knowledge, which may result in scientific discoveries.

AMOLF researchers Erik Garnett, Susan Rigter, and colleagues have demonstrated that amorphous perovskite exists. The material can significantly increase the efficiency of solar cells produced from perovskite.

Perovskites are naturally crystalline; in other words, the atoms pack together in an ordered pattern. From traditional silicon solar cells, we know that the efficiency of the cells can be boosted if a part of the material is amorphous, meaning the atoms pack together randomly. Erik Garnett from AMOLF was reportedly the first to realize that amorphous perovskite could fulfill the same function. The following challenge was to produce the material and study its properties. Garnett explains why that was difficult: 'Perovskite consists of ions. By nature, these easily organize in a crystal lattice, just like table salt, for example. We needed to come up with a trick to prevent those crystals from forming, and we managed to do just that. Using techniques such as X-ray diffraction, we subsequently also demonstrated that the material is amorphous. With this, we delivered the first irrefutable evidence that amorphous perovskite exists.'

Researchers from UCLA, NREL, The University of Toledo, Yangzhou University, Soochow University, Monash University and Lawrence Berkeley National Laboratory, have found that perovskites have a previously unutilized molecular component that can further tune the electronic property of perovskites.

Schematic of perovskite material with organic molecules that can add to its electronic properties. Credit: Jingjing Xue and Rui Wang/UCLA Samueli School of Engineering

Perovskite materials have a crystal-lattice structure of inorganic molecules like that of ceramics, along with organic molecules that are interlaced throughout. Up until now, these organic molecules appeared to only serve a structural function and would not directly contribute to perovskites' electronic performance.

Rice University scientists, in collaboration with a team from Los Alamos National Laboratory (LANL), have reported a technology that could dramatically reduce the cost of semiconductor electron sources, key components in various devices that range from night-vision goggles and low-light cameras to electron microscopes and particle accelerators.

Perovskite semiconductors (silver) treated with a layer of cesium (blue-green) could be tuned to emit free electrons (gray) over both visible and ultraviolet spectra (colored arrows), and a layer of cesium could regenerate degraded photocathodes.

Billions of dollars are spent each year on photocathode electron sources made from semiconductors containing rare elements like gallium, selenium, cadmium and tellurium. "This should be orders of magnitude lower in cost than what exists today in the market," said study co-corresponding author Aditya Mohite, a Rice materials scientist and chemical engineer. He said the halide perovskites have the potential to outperform existing semiconductor electron sources in several ways.

Scientists at Stanford University and the Department of Energy's SLAC National Accelerator Laboratory have used a novel method, based pressure from a diamond anvil cell, to stabilize lead halide perovskites and prevent them from breaking down at room temperature.

The team placed the regular version of the material, prone to instability, in a diamond anvil cell and squeezed it at a high temperature. This treatment reportedly "nudges" its atomic structure into an efficient configuration and keeps it that way, even at room temperature and in relatively moist air.