M: welcome to another episode of IMNANO
I: Putting the I in I M Nano, I am your host Irfani
M: and I am your other host, Monika
I: and today we will we talking about how nanotechnology can make electrons hop!
which what does that even mean?! Hopping electrons??! Nani desu ka!!?
M: hai so desu yo. yes that is so. Welcome to our LIT update segment. For this episode lets talk about research that was published in the journal of the American chemical society so JACS in December 2020 from Osaka University on improving intramolecular hopping through using organic molecules. So let’s unpack that sentence:
First off: what is an electron? Why do we want them to hop?
I: Electrons are the little tiny parts that make up atoms – they have a negative charge and kinda float around the center of the positive and neutral center of the atom. Atoms are the things in the periodic table like carbon lithium helium each of those letters on the periodic table is an atom and they can them come together and make molecules – so everything has electrons.
M: Electrons are everywhere, and they can move around given the right conditions. We want them to hop because they can carry signals faster, minimize lag so to speak.
This is important for developing the exciting new field of organic conductors – and organic in this case doesn’t mean from a range without pesticides – in this case, organic means containing mostly carbon, and then some oxygen, nitrogen, sulfur and or phosphorus.
I: so if a chemist comes up to me saying they do organic they mean they study carbon molecules and not my vegetables? That is very cool so these tiny molecules they designed them to be 10 nm in length or smaller – cool – so why is this particular article interesting? What makes it special?
M: Organic conductions these days when you actual build them into a prototype device strcuter their electrical conducvity decreases so it goes down a lot from the theoretical but in this work by Aso-sensi and colleagues, a new kind of rope or wire if you want to think of it that way, a logn chain was made from molecules with periodic twists that can carry electric current with less resistance
So these small molecules conduct electricity, and can be an alternative to electronic devices that are made of silicon – which silicon is the key part in our computers, cell phones, anything with a switch that powers on pretty much
I: very neat – so what are the molecules that they used?
M: they develop these wire made of up of oligothiophene – an oligomer and a thiophene : the oligomer is something between polymer and the monomer and a thiophene is a pentagon if we remembered from geometry class but its made out of atoms : 4 carbons and 1 sulfur
I: oh nice and Polymers are large molecules made of small, repeating molecular building blocks called monomers … so basically the monomer is ONE lego piece, if you put a few legos together less than 100 that’s an oligomer and then over 100 pieces, so many many, then you have the polymer, just make sure the lego pieces are the same and not random
M: yeah so overall the team designed, and tested wires made up of these oligothiophenes just one molecule thick and found them to work really well – they designed small clusters of the wires to have very close levels of energy to maximize conductivity so that electrons can hop faster
They did many arrangements and found that twisting the units works really well
I: What is unique about the twisting design?
M: when it is a straight chain or line of the wire, the levels of energy don’t match up – think of it like when you have to play leap frog but then you leap down and down and then have to leap up and down and up and down – you get tired really fast but if you were leaping at the same height so just in a straight line on the ground you travel faster right so same concept with electrons – the ground is the energy levels
Another way to picture it is if we think back to the 2008 journey to the center of the earth movie where the kid sean has to go across these magnetic floating rocks to get to the other side all the works need to be at the same level for him to hop over them and cross if he has to go hop down and some are higher than others it is a lot harder
I: so when the molecular wire is straight the energy levels are up and down and the electron has a hard time hopping around to the other side but when the wire has twists – then you can get the energy levels to match up and the electron can bounce in a straight line?
M: Yes and that is why this work is so interesting –the amount of work to have the hopping sites at the same energy and design the molecules to twist in a certain way took a lot of work not only for making the molecules but also the computational models and other experiments in the work
Overall, you align the steps to hope at the same energy, you lose less energy, improved transport
I: so this is truly for a class of devices that work at the nanoscale so neat
M: yeah really LIT work and carbon-based electronic devices require fewer toxic materials or harsh processing methods so really can revolutionize our world and are a very interesting and new field called organic materials
I: Nice find! Looking forward to what’s next...Link in the description to go read more. That’s all the nano for today, take care!
M: and stay curious!
Other sources:
Electrons hop to it on twisted molecular wires (Nanowerk News) Published December 29, 2020. Accessed January 17, 2021
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