Pixel: as small as it can get! // EIT Digital


Pixel: as small as it can get!

Artist impression of electroluminescence in a single polythiophene molecular wire (credit: Guillaume Schull, IPCMS (CNRS/Université de Strasbourg)

Pixels, those little points of light you see on a television screen today, have become smaller and smaller. The technology(ies) used to create these pixels has evolved and that has resulted in their shrinking. Evolution has led to more accurate colour rendering, more brightness, larger viewing angles and lower consumption.

Having smaller pixels means you can cram more of them in a given space, hence you increase the resolution. Also, once they get smaller than your visual acuity (the minimum distance between two points that you are able to separate one from the other) you only perceive a continuum, no longer a mosaic. On the web you will find many interpretations, and relative numbers (ranging from 8 to 600Mpixels), on the pixel numbers our eyes can capture, and the difference involves many factors, including brightness, colours, contrasts....However, speaking in plain language the smaller the pixel size, the more you can squeeze in a given space and the better the resolution. At density over 300 dot per inch our eyes can no longer separates two points (although up to 600 dpi our brain sometimes can tell the difference...).

We have seen plasma coming and now, almost, fading away (their pixels are the largest), LCD, LED, OLED, ... with the latter being the talk of the town in 2014, and the ones being used in the new 4k television screens.

How much smaller can a pixel become, to support higher resolutions, like the next generation of 8k screens?


Researchers are working on perfecting current technologies and on inventing new ones, like screens based on nanotechnologies.

I just run onto a news from the Institut Parisien de Chimie Moléculaire (CNRS/UPMC). In conjunction with researchers at IPCMS in Strasburg they have invented a pixel made by a single molecule (rendered in the figure).

The molecule used is a chain of polythiophene. This molecule when subjected to a flow of electrons, an electric current, emits photons. However, the photons are emitted only if the current flows in a specific direction. In practice they have built a Light Emitting Diode, a LED. Actually, polythiophene is already a component of commercial LEDs, the result here is the capability of using just one single molecule of it.

The amount of photons being produced by a single molecule of polythiophene is so small and the dimension so minuscule that there is no way our eye could see such a pixel. But what is interesting is that by having been able to reduce the pixel, the LED, to a single molecule let the researchers to study the interplay among electrons and photons at the quantum level and thus opens the way to improving the efficiency of LEDs, in the never ending quest for better performance and lower cost.

We are really reaching the Nature level of manipulating materials, and we can expect that in the next decade all the knowledge that is being harvested will translate into a transformation of our ambient. As our great grandparents could not have imagined the nineteen century transformation of cities and citizens way of life brought forward by cars, or our grandparents the changes brought forward by the cellphones and internet so we cannot start to imagine the changes resulting from ambient awareness, from the Internet of Things and with Things. And yet, we are crafting this change with our own hands.

Author - Roberto Saracco


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