Dear All,
I am fabricating an OFET based on quantum dots/organic SC hybrid, my first attempet failed when I tried to do a layer by layer solid ligand exchange to the quantum dot active layer (I used EDT, dacetonitrile, methanol, and the QD in toluene)
In a second batch I used mix of quantum dots/organic material in toluene without ligand exchange, and yet the device did not behave as transistor.
what could be the reason behind this?
your contributions are greatly appreciated
what is the used substrate?
As you can add a layer according to your substrate to increase adhesion.
I'm using a glass substrate patterns with ITO and PVP insulator, i used the layer by layer method with the materials mentioned above for QD deposition and ligand exchange.
the question is also regarding the amount of annealing and if it's possible to measure the device in ambient and not in glove box ?
What kind of QD materials do you use?
Generally QD was synthesized using long ligand (OA, Oam). When we make films of QD with long ligand, the films are resitive. We need to do ligand exchange first with shorter ligand such EDT, TBAI. In case of EDT, the acetonitrile is best solvent for doing ligand exchange. Different solvent also affect to the ligand exchange process.
If the case is you couldn't coated layer by layer (LbL) on top of ITO, In my experience... you need to wash the ITO first and do the UV ozone treatment. You can see my publication also since I am working on PbS QD solar cells.
Hopefully this can help you... gud luck!
Here the paper about Schottky devices which deposit PbS-QD on top of ITO. [http://dx.doi.org/10.1063/1.4804614] You can check the experimental section.
Dear Randi Azmi,
many thanks for your valuable contributions. in my case, my purchased QD is PbS capped with Olic ligands in toluene.
I do not suppose you fabricated the device in ambient air conditions, but i didn't see the glove box mentioned in your paper, or the use of any inert gas environment, can you confirm the environment condition of your device fabrication?
I am asking this because I'm searching for a way to either exchange or remove the ligands without having to use the expensive equipment such as the glove box. if you can think of any relevant works or publications I'd appreciate the share.
Hi Sara,
yes, exactly. We performed solid state ligand exchange in air condition.
Best!
Hi Randi,
I'm surprised to hear that because I was under the impression that lignad exchange performed in air can cause the quantum dots to degrade and effect the performance of the FET.
do you think this was only possible for you because you used the solar cell structure?
Do you think it would show similar results if I performed ligand removal instead of exchange ?
Hi Sara,
You can check other works from other reputed group.
Here you can check one of it.
Article Improved performance and stability in quantum dot solar cell...
You can check this below article too.
Article Integrating an electrically active colloidal quantum dot pho...
Please check this article too.
Article Interface Engineering in Hybrid Quantum Dot-2D Phototransistors
Many Thanks Randi, I'll proceed with the sources you provided and come back to you if needed.
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