a–d, Crystal structures of the 1CzTrz-F (a,b) and 3CzTrz-F (c,d) compounds, determined by XRD. a,c, Diagrams of the two dimers of both crystallographic unit cells to show the molecular packing. b,d, Spatial arrangement of the acceptor–donor contacts in the 3D crystal structure. The triazine acceptor and the carbazole donor units are coloured orange and blue, respectively. The green features in d indicate co-crystallized chloroform molecules. (Credit: Oskar Sachnik et al., 2023)

Eliminating Charge-Carrier Trapping In Organic Semiconductors

August 13, 2023 by Maya Posch 4 Comments

For organic semiconductors like the very common organic light-emitting diode (OLED), the issue of degradation due to contaminants that act as charge traps is a major problem. During the development of OLEDs, this was very pronounced in the difference between the different colors and the bandgap which they operated in. Due to blue OLEDs especially being sensitive to these charge traps, it still is the OLED type that degrades the quickest as contaminants like oxygen affect it the strongest. Recent research published in Nature Materials from researchers at the Max Planck Institute for Polymer Research by Oskar Sachnik and colleagues (press release) may however have found a way to shield the electron-carrying parts of organic semiconductors from such contaminants.

Current density (J)–voltage (V) characteristics of electron- and hole-only devices of 3CzTrz and TPBi. (Credit: Oskar Sachnik et al., 2023)

In current organic semiconductors TPBi is used for electron transport, whereas for this research triazine (Trz, as electron acceptor) and carbozole (Cz, as donor) were used and compared with the properties of leading-edge TPBi. While a few other formulations in the study did not show remarkable results, one compound (3CzTrz) was found using X-ray diffraction (XRD) to have a structure as shown on the right in the heading image, with the carbozole (in blue) forming essentially channels along which electrons can move, while shielded from contaminants by the triazine.

Using this research it might be possible to create organic semiconductors in the future which are free of charge-traps, and both efficiency and longevity of this type of semiconductor (including OLEDs and perovskites) can be improved immensely.

OLED Display Lets Vintage PC Engage Turbo Mode In Style

July 28, 2023 by Tom Nardi 10 Comments

Back in the 486 days, it was common to see a “Turbo” button on the front panel of many PCs, which was used to toggle between the CPU’s maximum speed and a slower clock rate that was sometimes necessary for compatibility with older software. Usually an LED would light up to show you were running at this higher speed, or if your machine was very fancy, it might even have a numerical display that would show the current CPU frequency.

[Joshua Woehlke] wanted to add a similar display to his 486, but figured that with modern technology, he could do something a bit more interesting. Especially when he realized that the spot on his case where the two-digit LED display would have originally been mounted was the perfect size to hold a common 0.96″ SSD1306 OLED. From there it was just a matter of wiring it up to an Arduino and writing some code to display different graphics depending on the computer’s current CPU speed.

Just like the frequency indicators of yore, the Arduino doesn’t actually measure the CPU’s frequency, it’s simply reading the state of the Turbo LED on the front panel. When the LED is off the Arduino shows an image of a i8088 CPU on the screen to indicate the computer is running in compatibility mode, and when the LED is on, the screen shows the Cyrix Cx486 DX2 logo. When the button hasn’t been pressed in awhile, the display defaults to a star field screensaver.

Regular readers may recall we recently covered a similar project that used an Arduino to add a little flair to an era appropriate seven-segment LED display. We’d say there’s still a good deal of romanticism about computers having a big “TURBO” button you can smash whenever you feel the need for speed.

Open Source OLED Nametag Is Full Of Features

July 20, 2023 by Donald Papp 5 Comments

Ever wanted a sweet OLED nametag with fancy features like daylight readability, automatic brightness adjustment, GIF animation support, all-day runtime, easy web interface, and more? [TobleMiner]’s OLED Nametag is the project you want to keep an eye on in that case.

It’s still an early prototype, but the feature list looks great and works with a variety of OLED modules that are easily available. The enclosure can be 3D printed, and while there is very little spare room inside the housing, [TobleMiner] has clearly made the most of all available space. Some PCB fab houses offer component placement these days, and the board is designed with exactly that in mind.

We’ve seen a batteryless E-paper display make a serviceable nametag in the past, and while those offer high contrast and wide viewing angles, they lack the sort of features this project is bursting at the seams with. Affordable access to good components and the ability to have high-quality PCBs made on demand has really raised the bar in terms of what a hacker project can work with in recent years, and we love to see it expressed in projects like this one.

These Fake Nixie Tubes Have A Bootup Screen

July 15, 2023 by Donald Papp 34 Comments

[IMSAI Guy] bought a fake Nixie clock, and luckily for all of us has filmed a very close look and demonstration. Using OLED displays as the fake Nixie elements might seem like cheating to some, the effect is really very well done.

Clock digits with bootup screens is something we didn’t know we liked until we saw it.

When it comes to Nixie elements, it’s hard to say which gets more attention and project time from hardware folks: original Nixie tube technology, or fake Nixie elements. Either way, their appeal is certainly undeniable.

Original Nixie tubes have shown up in modern remakes of alarm clocks, and modern semiconductors make satisfying a Nixie tube’s power requirements much easier with clever and compact Nixie drivers costing under $3 USD. This is also a good time to remind people that Nixie tubes don’t have to be digits. This audio spectrum visualizer, for example, uses IN-13 tubes which serve as elements of a bar graph.

Authentic Nixie elements require high voltages and are labor-intensive to manufacture to say the least, and as far as fake Nixie elements go, this one looks pretty good once it lights up. You can see it in action in the video, embedded below.

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Smooth Animations, Slick Bar Graphs, But No Custom Characters On This 16×2 OLED

April 27, 2023 by Dan Maloney 7 Comments

Sometimes, finding new ways to use old hardware requires awesome feats of reverse engineering, software sleight of hand, and a healthy dose of good fortune. Other times, though, it’s just as simple as reading the data sheet and paying attention to details.

Not that we’re knocking [upir]’s accomplishment with these tricked-out 16×2 OLED displays. Far from it, in fact — the smoothly animated bar graph displays alphanumerics look fantastic. What’s cool about this is that he accomplished all this without resorting to custom characters. We’ve seen him use this approach before; this time around, the hack involves carefully shopping for a 16×2 OLED display with the right driver chip — a US2066 chip. You’ll still need a few tricks to get things working, like extra pull-up resistors to get the I2C display talking to an Arduino, plus a little luck that you got a display with the right character ROM.

Once all that is taken care of, getting the display to do what you want is mainly a matter of coding. In the video below, [upir] does a great job of walking through the finer points, and the results look great. The bar graphs in particular look fantastic, with silky-smooth animations.

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Magic 8 Ball Provides Tech Support

March 28, 2023 by Bryan Cockfield 15 Comments

ChatGPT might be making the news these days for being able to answer basically any question it’s asked, those of us who are a little older remember a much simpler technology that did about the same thing. The humble “Magic 8 Ball” could take nearly the same inputs, provided they were parsed in simple yes/no form, and provide marginal help similar to the AI tools of today. For a toy with no battery or screen, this was quite an accomplishment. But the small toy couldn’t give specific technical support help, so [kodi] made one that can.

The new 8 Ball foregoes the central fluid-filled chamber for an STM32 Blue Pill board with a few lithium batteries to power it. The original plastic shell was split in two with a hacksaw and fitted with a 3D printed ring which allows the two halves to be reconnected and separated again when it needs to charge. It uses a circular OLED to display the various messages of tech support, which are displayed when an accelerometer detects that the toy has been shaken.

Granted, most of the messages are about as helpful to solving a tech support issue as the original magic 8 Ball’s would have been, but we appreciate the ingenuity and carefree nature of a project like this. It also did an excellent job at operating in a low-power state as well, to avoid needing to charge it often. There have been a few other digital conversions of these analog fortune tellers as well, like this one which adds GIFs to each of the original answers.

DOOM Ported To A Single LEGO Brick

March 18, 2023 by Lewin Day 18 Comments

By now you’ve all seen the tiny LEGO brick with a working screen in it. The work of one [James “Ancient” Brown], it was truly a masterpiece of miniaturization and creativity. Since then, [James] hasn’t stopped innovating. Now, he’s demoing a playable version of DOOM running on a single plastic brick.

We’ve covered the construction of these astounding screen bricks before. Long story short, [James] designed a tiny PCB that hosts an RP2040 microcontroller which is then hooked up to a tiny OLED screen. The components are placed in a silicone mold, which is then filled with transparent resin to form the brick. The screen is then powered via contacts in the bottom, much like older-style LEGO motors.

Early experiments involved running various graphics to emulate a spaceship dashboard, but [James] has now gone much further. He’s implemented RP2040-doom to run the game. It uses tilt controls thanks to an accelerometer, combined with capacitive touch controls for shooting. The monochrome OLED is driven very fast with a special library of [James’] own creation to create three levels of grayscale to make the game actually visible and (just barely) playable.

It’s a hack, of course, and the controls are far from perfect. Nobody’s speed-running E1M1 on [James’s] LEGO brick, to be sure. Perchance. With that said, it’s still a glorious piece of work nonetheless. Just imagine, sitting with friends, and announcing you’re going to play some DOOM — only to pluck a piece of LEGO out of your pocket and start blasting away at demons.

Just because [James] doesn’t know when to quit, we’re going to lay down the gauntlet. Let’s get network play happening on these things, yeah?
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