Does size really matter?

Well, it surely does according to Mungiba Wendi, Louis Bruce and Alexei Yekimov, the

2023 Chemistry Nobel Prize laureates.

They are the pioneers of the development of quantum dots, nanoparticles so tiny that quantum

effects determine their optical behavior.

When particles are so small they can be measured in millions of millimeters, strange phenomena

start to occur.

When it comes to their optical properties, quantum dots do not behave neither as bulk

materials nor as molecules.

If we manage to carefully control how the particles are formed, we can finely tune their

color and use them for screens and solar cells.

In CRC 1411, Pia Doreseghetz works on scaling up the synthesis of quantum dots while keeping

the control over their size required for optical applications.

So Dorese, what is so special about quantum dots?

Quantum dots are fascinating nanomaterial because of their beautiful colors.

So if you have a quantum dot, this is a semiconductor material, so the same material as we also

have in our electronic devices.

However, here it's in the form of a nanoparticle.

So that means a very small particle, just a few nanometers in diameter.

If you have this, then the band gap of these materials is becoming a function of the particle

diameter.

This is what we call the quantum size effect.

And this in turn has the effect that the colors of this material is becoming a function of

the particle size.

And this of course provides a lot of opportunities and I always find it quite intriguing with

these materials that they appear like a colorless solution because the particles are too small

that you can see them by naked eye.

However, if you change reaction parameters like the temperature or the synthesis time,

then you see how gradually these colors are changing.

And this is really wonderful to observe, I think.

And what exactly does your lab do?

Yeah, we are engineers and as engineers, the ultimate key question we want to answer or

address is how we can generate these materials in a reproducible and scalable manner.

And to do this, in the first stage, we implemented a methodology for characterization of these

materials based on their optical properties.

And then next what we did was set up a fully automated platform for high throughput experimentation

or high throughput synthesis of these materials.

So this platform consists of six reactors that can be operated fully independently

from each other with regard to the reaction temperature, the mixing inside these reactors,

the reaction composition and the dosing.

And this now allows us to perform also screenings of huge parameter spaces.

And ultimately, if you think about that, we were able to manage precise dosing and synthesis

up to 350 degrees C in the reaction solution.

This is something that we are pretty proud of because this is not trivial.

What was the most challenging part of building a reactor?

Yeah, actually, there were two challenges we had to overcome.

So the first one was reproducibility.

So we managed to have what we call ultra reproducible particle synthesis.

This we achieved by having a defined mixing or very good mixing in our reactors.

Mixing is important to achieve narrow particle size distribution and does nanomaterials with