Perovskite lasers - Page 3

An international team of researchers has announced the development of the world's most compact perovskite-based semiconductor laser that works in the visible range at room temperature. According to the authors of the research, the laser is a nanoparticle of only 310 nanometers in size (which is 3,000 times less than a millimeter) that can produce green coherent light at room temperature.

The scientists succeeded in exploiting the green part of the visible band, which was considered problematic for nanolasers. "In the modern field of light-emitting semiconductors, there is the 'green gap' problem," says Sergey Makarov, principal investigator of the article and professor at the Faculty of Physics and Engineering of ITMO University. "The green gap means that the quantum efficiency of conventional semiconductor materials used for light-emitting diodes falls dramatically in the green part of the spectrum. This problem complicates the development of room temperature nanolasers made of conventional semiconductor materials."

An all-inorganic perovskite micro/nano-structure has been demonstrated by a collaborative team of researchers from Shanghai Institute of Optics and Fine Mechanics of the Chinese Academy of Sciences (CAS), Shanghai Institute of Technical Physics of CAS and Nanjing Xiaozhuang University, that is believed to be a promising candidate for achieving high-performance nano-lasers.

Semiconductor nano-lasers with high spectral purity and stability, namely single-mode nano-lasers, are very desirable in color laser display, on-chip optical communication and computing. To date, most of reported nano-lasers exhibit multi-mode structure resulting from in-homogeneous gain saturation, while the realization of high-quality single-mode laser is very challenging and is largely limited by the cavity structure and the properties of the gain medium.

A collaborative study between Tel Aviv University (TAU) in Israel and Karlsruhe Institute of Technology (KIT) in Germany demonstrates remarkable continuous lasing action in devices made from perovskites.

"In contrast to previous studies around the world, this is the first study to exhibit continuous lasing action, as opposed to pulsed operation," says Prof. Jacob Scheuer of TAU's Department of Physical Electronics, who led the TAU team of researchers. "This family of materials is considered the most promising candidate for a future laser-based industry, because their fabrication is simple, fast and inexpensive compared to current semiconductor materials being used for these purposes. In addition, these materials can support the realization of solid-state lasers emitting in green, necessary for future lighting, displays and projectors," Prof. Scheuer adds. "Current semiconductor lasers emit light only in red and blue."

An international research team has developed a new method of synthesizing miniature light sources. The method is based on a unique laser which produces millions of nanolasers from a perovskite film in a few minutes. Such lasers look like small disks, work at room temperature and have a tunable emission wavelength from 550 to 800 nm. The high speed and good reproducibility of this method make it promising for the industrial production of single nanolasers as well as whole chains.

A scheme of the synthesis and operation and an image of the final nanolasers

Such miniature light sources or nanolasers are required, for example, for producing optical chips that could process information in next-gen devices. However, making such light sources is generally not that easy due to unstable materials, as well as the complex and expensive fabrication methods, which are difficult to control and adjust for industrial production. The scientists from ITMO, the Far Eastern Federal University, Texas University at Dallas, and the Australian National University have found a new way to solve this problem. They have developed a method that may enable the creation of millions of nanolasers from an optically active halide perovskites in a few minutes.

A research team composed of scientists from Michigan State University and University of Michigan has deployed a new approach to growing all inorganic lead-free halide perovskites.

"Epitaxial growth has long since revolutionized the study of many electronic materials including silicon, oxide perovskites, and III-V semiconductors," said Richard Lunt, an Associate Professor at Department of Chemical Engineering and Materials Science, Michigan State University who has supervised the project. "There is very little known about the epitaxial growth of halide perovskites, but these exciting materials hold enormous potential. This has motivated us to explore this entirely new research area."

UK-based Ossila provides components, equipment and materials to enable faster and smarter organic electronics research and discovery. Ossila provides both materials and equipment for perovskite researchers, and the company's lead perovskite scientist, Dr. Jonathan Griffin, was kind enough to answer a few questions we had for him.

Thanks to improved knowledge about salt-solvent interactions, single crystals of perovskites can now be grown. Pictured above are several single-crystal MAPbBr perovskites, alongside the seed crystals used to grow these crystals

Dr. Griffin holds nearly a decade of experience working in organic photovoltaic research and over 5 years of working with perovskites. At Ossila, Jonathan works on technical support for several material ranges, including perovskites, organic photovoltaics, graphene and other 2-D materials. He is also involved in the development of new test equipment and product ranges. Prior to this, he worked in a postdoctoral research position at the University of Sheffield.

Q: Thank you for your time Dr. Griffin. Can you detail for us Ossila's perovskite product range in general?

Researchers at the U.S. Naval Research Laboratory (NRL) Center for Computational Materials Science, working with an international team of physicists, have found that nanocrystals made of cesium lead halide perovskites (CsPbX3), is the first discovered material which the ground exciton state is "bright," making it an attractive candidate for more efficient solid-state lasers and light emitting diodes (LEDs).

The work focused on lead halide perovskites with three different compositions, including chlorine, bromine, and iodine. Nanocrystals made of these compounds and their alloys can be tuned to emit light at wavelengths that span the entire visible range, while retaining the fast light emission that gives them their superior performance.

Researchers from Penn State and Princeton University have made strides in creating a diode laser based on a perovskite material that can be deposited from solution on a laboratory benchtop.

Organic diode lasers, that are extremely hard to make, are sought after since they have many advantages. First, because organic semiconductors are relatively soft and flexible, organic lasers could be incorporated into new form factors not possible for their inorganic counterparts. While inorganic semiconductor lasers are relatively limited in the wavelengths, or colors, of light they emit, an organic laser can produce any wavelength a chemist cares to synthesize in the lab by tailoring the structure of the organic molecules. This tunability could be very useful in applications ranging from medical diagnostics to environmental sensing.

Researchers from KU Leuven from the Roeffaers Lab and the Hofkens Group have discovered a new way to create the sought-after dark alpha-phase perovskite. They used direct laser writing (tuned intense laser light) to locally heat the perovskite surface, making it change from the (useless) delta state to the (highly desirable) alpha state.

Furthermore, they also found that the material now remained in this state for many weeks, even at room temperature, without further need of a stabilizing treatment. The scientists further managed to use the laser beam to rapidly micro-fabricate complex patterns of the dark FAPbI3 state. "These findings are a big step forward in locally tailoring the structural, electrical, and optical properties of an important new class of materials and provides an avenue for making customised optical devices, all on demand".

Researchers at the Department of Energy's Lawrence Berkeley National Laboratory (Berkeley Lab) have demonstrated that halide perovskites are capable of discharging multiple, bright colors from just one nanowire at resolutions as small as 500 nm. This work could impact the development of new applications in optoelectronics, nanoscopic lasers, photovoltaics and more.

The team used electron beam lithography to fabricate halide perovskite nanowire heterojunctions, the junction of two types of semiconductors. The researchers analyzed cesium lead halide perovskite, and then used a common nanofabrication method integrated with anion exchange chemistry to switch out the halide ions to form cesium lead bromide, cesium lead iodide and cesium lead chloride perovskites. Each difference resulted in a different color discharged.