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Perovskite Leads to 100-Percent Efficient Nanowire Lasers

The quality that makes perovskite attractive for photovoltaics makes them near perfect for lasers

2 min read
Perovskite Leads to 100-Percent Efficient Nanowire Lasers
Image: Song Jin/University of Wisconsin-Madison

Last year, perovskites established themselves as the “next big thing” in photovoltaic materials, with energy conversion efficiency numbers reaching as high as 20 percent.

Now researchers at the University of Wisconsin-Madison have demonstrated that perovskites can produce high-efficiency, ultra small lasers.

“While most researchers make these perovskite compounds into thin films for the fabrication of solar cells, we have developed an extremely simple method to grow them into elongated crystals that make extremely promising lasers,” said Song Jin, a professor at the University of Wisconsin-Madison, in a press release.

In research published in the journal Nature Materials, Jin and his colleagues produced the perovskite material in a simple chemical solution process that resulted in nanoscale rectangular crystals of the perovskite that, because of their scale and dimensions, are dubbed nanowires.

“The single-crystal perovskite nanowires, grown from solutions at room temperature, are high quality, almost free of defects, and they have the nice reflective parallel facets that a laser needs,” Jin said in the release. “Most importantly, according to the conventional measures of lasing quality and efficiency, they are real standouts.”

In measurements, the nanowire lasers proved to be 100 percent efficient, meaning that every photon they absorbed was used to produce a photon of laser light. According to one of Jin’s collaborators, Ziaoyang Zhu of Columbia University, this level of efficiency is one order of magnitude greater than other nanowire lasers.

“These are simply the best nanowire lasers by all performance criteria, even when compared to materials grown in high temperature and high vacuum,” said Jin. “Perovskites are intrinsically good materials for lasing, but when they are grown into high-quality crystals with the proper size and shape, they really shine.”

In further research, the aim will be to improve the chemical stability of the nanowire lasers and to stimulate the lasers with electricity rather than just light.

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3 Ways 3D Chip Tech Is Upending Computing

AMD, Graphcore, and Intel show why the industry’s leading edge is going vertical

8 min read
A stack of 3 images.  One of a chip, another is a group of chips and a single grey chip.
Intel; Graphcore; AMD

A crop of high-performance processors is showing that the new direction for continuing Moore’s Law is all about up. Each generation of processor needs to perform better than the last, and, at its most basic, that means integrating more logic onto the silicon. But there are two problems: One is that our ability to shrink transistors and the logic and memory blocks they make up is slowing down. The other is that chips have reached their size limits. Photolithography tools can pattern only an area of about 850 square millimeters, which is about the size of a top-of-the-line Nvidia GPU.

For a few years now, developers of systems-on-chips have begun to break up their ever-larger designs into smaller chiplets and link them together inside the same package to effectively increase the silicon area, among other advantages. In CPUs, these links have mostly been so-called 2.5D, where the chiplets are set beside each other and connected using short, dense interconnects. Momentum for this type of integration will likely only grow now that most of the major manufacturers have agreed on a 2.5D chiplet-to-chiplet communications standard.

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