Team members Madeleine Laitz, left, and lead author Dane deQuilettes stand in front of a tidy lab bench equipped with oscilloscopes and computers. Laitz has a snazzy yellow jacket that pops compared to the neutrals and blues of the rest of the picture.

More Progress On Perovskite Solar Cells

March 8, 2024 by Navarre Bartz 20 Comments

Perovskites hold enormous promise for generating solar energy, with the potential to provide lighter and cheaper cells than those made from silicon. Unfortunately, the material breaks down too rapidly to be practical for most applications. But thanks to some recent research, we now have a better understanding of the nanoscale changes that happen during this breakdown, and how to combat it.

The research is focused on the topic of passivation, which seeks to increase the useful lifespan of perovskites by studying the surface interface where they meet other materials. Most of the perovskite material is a perfect latticework of atoms, but this structure is broken at the surface. This atomically “jagged” interface introduces losses which only get worse over time. Currently, the best way to address this issue is to essentially seal the surface with a very thin layer of hexylammonium bromide.

While this technique significantly simplified the passivation process when it was discovered, the effect had yet to be adequately characterized to further advance the field. According to lead author, [Dane deQuilettes], “This is the first paper that demonstrates how to systematically control and engineer surface fields in perovskites.”

Prefer to roll your own cells? How about a DIY dye sensitized cell or this thermionic converter model?

When Hacking And Biosensing Collide

December 24, 2021 by Elliot Williams 2 Comments

[Prof. Edwin Hwu] of the Technical University of Denmark wrote in with a call for contributions to special edition of the open-access scientific journal Biosensors. Along the way, he linked in videos from three talks that he’s given on hacking consumer electronics gear for biosensing and nano-scale printing. Many of them focus on clever uses of the read-write head from a Blu-ray disc unit (but that’s not all!) and there are many good hacks here.

For instance, this video on using the optical pickup for the optics in an atomic force microscope (AFM) is bonkers. An AFM resolves features on the sub-micrometer level by putting a very sharp, very tiny probe on the end of a vibrating arm and scanning it over the surface in question. Deflections in the arm are measured by reflecting light off of it and measuring their variation, and that’s exactly what these optical pickups are designed to do. In addition to phenomenal resolution, [Dr. Hwu’s] AFM can be made on a shoestring budget!

Speaking of AFMs, check out his version that’s based on simple piezo discs in this video, but don’t neglect the rest of the hacks either. This one is a talk aimed at introducing scientists to consumer electronics hacking, so you’ll absolutely find yourself nodding your heads during the first few minutes. But then he documents turning a DVD player into a micro-strobe for high speed microfluidics microscopy using a wireless “spy camera” pen. And finally, [Dr. Hwu’s] lab has also done some really interesting work into nano-scale 3D printing, documented in this video, again using the humble Blu-ray drive, both for exposing the photopolymer and for spin-coating the disc with medium. Very clever!

If you’re doing any biosensing science hacking, be sure to let [Dr. Hwu] know. Or just tear into that Blu-ray drive that’s collecting dust in your closet.

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Ask Hackaday: Building Nano Scale Antennas

March 28, 2012 by Brian Benchoff 70 Comments

As an RF engineering student, [Camerin] is usually tasked with pointless yet educational endeavors by his advisor and professors. Most of the time (we hope) he sees the task through and ends up pulling something out of his hat, but a few days ago a professor dropped a bombshell on him. After reading this article on nano scale antenna fabrication, a professor asked [Camerin] if it was possible to build a 3D inkjet printer with a ludicrous amount of accuracy and precision.

The full article, Conformal Printing of Electrically Small Antennas on Three-Dimensional Surfaces, was recently published in Advanced Materials and is available via Google Scholar. The jist of the article is that three-dimensional antennas printed on a sphere approach the physical limits of how good an antenna can be. To test out these small, spherical antennas, the authors of the paper built an extremely high-precision 3D inkjet printer that draws antenna traces on a glass sphere with conductive ink.

The positional accuracy of this printer is 50 nanometers, or about half the size of an HIV virus. The conductive silver ink is delivered by a nozzle with a diameter of 100 to 30 µm and prints onto a glass sphere about 6 mm in diameter. This is a level of precision that companies and research institutions pay top dollar for, so we’re left wondering how the authors built this thing.

We’re turning this question over to the astute readers of Hackaday: how exactly would you build a 3D inkjet printer with this much accuracy and precision? Would it even need to be that precise? Post your answer in the comments.