I have been trying to study the band offset engineering in fullerene organic solar cells. I came across some research articles on heterojunction solar cells which used the Anderson's electron affinity model for band offset analysis. Can we use the model to analyse the band offsets in organic bulk heterojunction solar cells?
Dear Nithya K S ,
Welcome!
There are rules governing the energy level matching among the different layers of the organic bulk heterojunction solar cells.
These rules are:
- The effective energy gap of the donor acceptor material is = Ela-Ehd
- The electron transport layer and the hole transport layer contacting the acceptor and the donor layer must have energy levels such that one gets the maximum contact difference of potential between them and this energy difference must approach the effective energy gap of the donor acceptor blend.
- Both ETL and HTL must be heavily doped to make their Fermi level coincide with the conduction band edge of the ETL and the valence band edge of the HTL.
Conversely the HTL must reflect the electrons back to the active material and the ETL must reflect the holes to the active layer.
So the energy gaps of both ETL and HTL must be larger than the effective energy gap of the blend.
These are the rules of the energy level matching in the organic solar cells.
Please for morfe information please follow the papers:Conference Paper Generic Analytical Models for Organic and Perovskite Solar Cells
and the paper: Article Possible efficiency boosting of non-fullerene acceptor solar...
and the paper
Article Numerical study of organic graded bulk heterojunction solar ...
The first papers brings the rules in an analytical way
and the two others show the effect of band edge offsets between the blend and both the ETL and the HTL.
You can project this study on the intended paper and compare between them.
Best wishes
Anderson's rule is used for the construction of energy band diagrams of the heterojunction between two semiconductor materials. Anderson's rule states that when constructing an energy band diagram, the vacuum levels of the two semiconductors on either side of the heterojunction should be aligned (at the same energy)
Hi Hadi Jabbar Alagealy
How to align the vacuum levels of the two semiconductors ? Could you help me with this.
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