Why MoO3 is not widely used as a hole transport layer in Perovskite solar cells. The value is valance band in MoO3 is 5.3eV and it is matching with the Valance band of Perovskite (5.3eV) although is it not used. The fermi level of MoO3 is 6.9eV. Whether femi level has any role in this
Dear Pratheek,
welcome,
I will show here only how one can judge the suitability of a material as a HTL.
The hole transport layer must satisfy the following requirements to work properly:
- High conductivity which means high free hole concentration and high mobility
- Energy levels matching:
which means the conduction band edge lies above that of the perovskite to the reject the electrons towards the cathode and the valence band edge lies above the that of the perovskite to extract holes from the pervoskite layer.
- Its Fermi level must lie as much as possible under the Fermi level of the electron transport layer to achieve as high as contact of potential difference. This condition is required for as high as possible opencircuit voltage.
- It must have low interface state with the pervoskite to reduce the recombination at the interface
- It must build an ohmic contact with the metal electrode layer.
- Easy to fabricate as a thin film on perovskite layer.
I would like that you list the properties of your material ans check how much it satisfies the above requirements.
For more information please refer to the recent paper: Conference Paper Generic Analytical Models for Organic and Perovskite Solar Cells
If you find it useful please recommend it for your colleagues.
Best wishes
This was the requirement on the hole transport layer. Let us now extend the answer to shed more light on the issue.
MoO3 is a conductive oxide behaving as a metal like n type material. So, from this point of few it can suit the electron transport layer not the hole transport layer. But the cause of not using it as an electron transport layer its high work function which render it as a good candidate as an anode and consequently as a hole collecting layer since its Fermi level will lie slightly above the valence band edge of the active layer.
In this view this material is working as a substitute of metallic anode rather than a classical hole transport material.
For more information about the energy levels of MoO3 please follow the link: https://www.repository.cam.ac.uk/bitstream/handle/1810/246746/APL-MoO3.pdf;jsessionid=80B4167A93D127A8ACD621C4ACE5D80D?sequence=1
Best wishes
Hi Pratheek,
In addition to Abdelhalim abdelnaby Zekry 's inputs refer to this publication. they have studied exactly (Title: High-Work-Function Molybdenum Oxide Hole Extraction Contacts in Hybrid Organic−Inorganic Perovskite Solar Cells ) what you are seeking, suggested it does not work to yield high efficiency!
https://www.osti.gov/pages/servlets/purl/1337615
all the best.
In addition to what is already being told here, please refer to a good review article ()Article Energy Level Alignment at Interfaces in Metal Halide Perovsk...
where a dedicated section is written to answer your question ( 6.3.5. Perovskite/MoO3 Interface). Hope it helps- Badges
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