Perovskite materials - Page 4

Stanford researchers have found a way to create and stabilize an extremely rare form of gold that has lost two negatively charged electrons, denoted Au²⁺. The material stabilizing this elusive version of the valued element is a halide perovskite. Surprisingly, the Au²⁺ perovskite is also quick and simple to make using off-the-shelf ingredients at room temperature.

"It was a real surprise that we were able to synthesize a stable material containing Au²⁺—I didn't even believe it at first," said Hemamala Karunadasa, associate professor of chemistry at the Stanford School of Humanities and Sciences and senior author of the study. "Creating this first-of-its-kind Au²⁺ perovskite is exciting. The gold atoms in the perovskite bear strong similarities to the copper atoms in high-temperature superconductors, and heavy atoms with unpaired electrons, like Au²⁺, show cool magnetic effects not seen in lighter atoms."

Researchers from Southeast University in Bangaladesh and U.S-based Rochester Institute of Technology have examined the performance of a lead-free Cs₂TiX₆-based n–i–p type heterostructure perovskite solar cell design, performed using a one-dimensional device simulator, also known as the SCAPS-1D. 

The design makes use of Cs₂TiCl₆ as an n-type front absorber, Cs₂TiI₆ as an I (intrinsic)-layer absorber and Cs₂TiBr₆ as a p-type absorber. NiO (p) and ZnO (n) are utilized as the hole transport material and electron transport material. The fluorine-doped tin oxide (FTO) acts as a front contact, conductive oxide, while Pt (platinum) is used as the back contact. 

Australia-based Greatcell Solar Materials produces and supplies perovskite materials, and is one of the industry's pioneer companies. We conducted an interviw with Dr. Yanek Hebting, Greatcell's general manager, who updates us on the company's business, material and his views on the perovskite industry.

Hello Dr. Hebting, Thank you for this Q&A. Can you introduce us to Greatcell Solar Materials?

Greatcell Solar Materials Pty Ltd was created in October 2018 as the spin-off of the Materials Division of Greatcell Solar, formerly Dyesol. Greatcell Solar Materials is a manufacturer and supplier of materials (including perovskite precursors, dyes, ligands, titania pastes, electrolytes as well as components) for energy system applications to the photovoltaics research sector and the electronics industry.

All products are manufactured and shipped from our facility in Queanbeyan, NSW Australia.

Can you tell us a bit about the demand for perovskite materials? Does it come mostly for research, or pilot lines?

As COVID restrictions around the world have eased and global activity resumed, the demand for perovskite materials has significantly increased since.
Greatcell Solar Materials provides both bulk quantities for industrial partners as well as small quantities for research purposes. The demand for research purpose will always be a part of the demand, it is exciting to see some pilot lines take fruition and begin the process of commercialization.

Researchers from Duke University, Purdue University,  Yale University, Lawrence Berkeley National Laboratory, Chinese Academy of Sciences (CAS), Westlake University and Huazhong University of Science and Technology have demonstrated that by limiting the arrangement of multiple inorganic and organic layers within crystals using a novel technique, they can regulate the energy levels of electrons and holes (positive charge carriers) within perovskites.

This tuning capability affects the materials’ optoelectronic properties and capacity to emit light of specific energies, as illustrated by their ability to function as a laser source.

Researchers from Japan's Tokyo Institute of Technology, University of Oxford in the UK and Colorado State University in the U.S have shown that α-FAPbI₃, a promising solar cell material with a cubic perovskite structure that is metastable at room temperature, can be stabilized by introducing a pseudo-halide ion like thiocyanate (SCN^–) into its structure. The recent findings provide new insights into the stabilization of the α-phase via grain boundary and pseudo-halide engineering.

A material with good photophysical properties that has recently gained momentum is α-formamidinium lead iodide or α-FAPbI₃ (where FA⁺ = CH(NH₂)₂⁺), a crystalline solid with a cubic perovskite structure. Solar cells made of α-FAPbI₃ exhibit a remarkable 25.8% conversion efficiency and an energy gap of 1.48 eV. Unfortunately, α-FAPbI₃ is metastable at room temperature and undergoes a phase transition to δ-FAPbI₃ when triggered by water or light. The energy gap of δ-FAPbI₃ is much larger than the ideal value for solar cell applications, making the preservation of the α-phase crucial for practical purposes. To overcome this problem, the team of researchers, led by Associate Professor Takafumi Yamamoto from Tokyo Institute of Technology (Tokyo Tech), has recently presented a new strategy for stabilizing α-FAPbI₃.

Researchers from The University of Texas at Austin, University of Pennsylvania and Massachusetts Institute of Technology (MIT) have addressed the question of how lattice dynamics in layered hybrid perovskites are affected by the dimensional engineering of the inorganic frameworks and their interaction with the molecular moieties. 

The team tackled this question by using a combination of spontaneous Raman scattering, terahertz spectroscopy, and molecular dynamics simulations. This approach reveals the structural dynamics in and out of equilibrium and provides unexpected observables that differentiate single- and double-layered perovskites.

Researchers from Duke University and North Carolina State University have reported glass formation for low-melting-temperature 1-MeHa₂PbI₄ (1-MeHa = 1-methyl-hexylammonium) using ultrafast calorimetry, thereby extending the range of metal halide perovskite (MHP) glass formation across a broader range of organic (fused ring to branched aliphatic) and halide (bromide to iodide) compositions. 

A few years ago, Akash Singh and collaborators at Duke University set out to explore the realm of glassy perovskites, a departure from the traditionally studied crystalline perovskites. Since then, this topic sparked interest, resulting in the establishment of a novel research domain centered around glass-forming hybrid perovskite semiconductors with reversible switching. This recent discovery of glass formation in MHPs opens new opportunities associated with reversible glass-crystalline switching, with each state offering distinct optoelectronic properties. However, the previously reported [S-(−)-1-(1-naphthyl)ethylammonium]₂PbBr₄ perovskite is a strong glass former with sluggish glass-crystal transformation time scales, pointing to a need for glassy MHPs with a broader range of compositions and crystallization kinetics.   

Researchers from Texas A&M University, Northwestern University, University of South Florida and University of Illinois Urbana-Champaign have studied the fatigue behavior of 2D hybrid organic-inorganic perovskites (HOIPs) in practical applications.

The application of repeated or fluctuating stresses below the material's strength, known as fatigue loading, often leads to failure in 2D hybrid materials. However, the fatigue properties of HOIP materials have remained elusive despite their widespread use in various applications. The research group demonstrated how fatigue loading conditions, wearing different components, would affect the lifetime and failure behavior of the materials. Their results provide insights into designing and engineering 2D HOIPs and other hybrid organic-inorganic materials for long-term mechanical durability.

Researchers from North Carolina State University, National Synchrotron Light Source II at Brookhaven National Laboratory and Rey Juan Carlos University have created a novel materials acceleration platform (MAP), essentially a robot capable of conducting experiments more efficiently and sustainably to develop a range of new semiconductor materials with desirable attributes. The researchers have demonstrated that the new technology, called RoboMapper, can rapidly identify new perovskite materials with favorable properties and improved potential for creating stable and efficient solar cells.

“RoboMapper allows us to conduct materials testing more quickly, while also reducing both cost and energy overhead – making the entire process more sustainable,” says Aram Amassian, corresponding author of a paper on the work and a professor of materials science and engineering at North Carolina State University.

Researchers at MIT have prepared large CsPbBr₃ nanocrystals and observed direct evidence of interference between indistinguishable single photons sequentially emitted from a single nanocrystal. 

While the work is currently a fundamental discovery of these materials' capabilities, it might ultimately pave the way to new optically based quantum computers, as well as possible quantum teleportation devices for communication, the researchers say.