Hi dear colleagues,
I am fabricating an organic photovoltaic device with the structure ITO/PEDOT: PSS/ P3HT: PC70BM/ Al, and the obtained IV relationship was found to be linear rather than exponential. I am guessing that behavior might be a result of high series resistance and/or low shunt resistance, so can anyone help me improve this behavior or have any other suggestions?
In addition, the device performance was dramatically reduced after device annealing.
- Can Silver electrode or Al with purity of (99.995%) work better?
Please be aware of the following which may help:
1- PEDOT:PSS and the active layer solutions were spin coated without any filtration.
2- Thickness of the metal electrode (Al) was 75 nm.
3- Al evaporation is conducted outside the glovebox.
4- HTL was annealed at 150 degrees Celsius for 10 minutes and the whole device was also annealed inside the glovebox at the same temp. for 15 minutes.
5- Devices were tested without encapsulation.
6- Purity of Al wire was 99.98%.
Thanks in advance.
The first steno in trouble shooting the solar cell is to measure the dark current.
Plotting the two the dark and illuminated I-V curves with each others gives information about the how strong the electric field and the recombination in the D/A layer.
It seems that the major effect here is the high series resistance rather the smaller short resistance as you have an S-type curve.
I see that you have to increase the thickness of the metal .
Decrease the thickness of the the HTL.
Also make the blend thickness as small to just absorb the incident radiation.
But the major help can be achieved by using an ETL to achieve energy level matching withe the lumolevel of the acceptor layer.
The simulation study in this paper may help you to enhance your cell.
https://www.researchgate.net/publication/332029371_Possible_efficiency_boosting_of_non-fullerene_acceptor_solar_cell_using_device_simulation
Best wishes
The first steno in trouble shooting the solar cell is to measure the dark current.
Plotting the two the dark and illuminated I-V curves with each others gives information about the how strong the electric field and the recombination in the D/A layer.
It seems that the major effect here is the high series resistance rather the smaller short resistance as you have an S-type curve.
I see that you have to increase the thickness of the metal .
Decrease the thickness of the the HTL.
Also make the blend thickness as small to just absorb the incident radiation.
But the major help can be achieved by using an ETL to achieve energy level matching withe the lumolevel of the acceptor layer.
The simulation study in this paper may help you to enhance your cell.
https://www.researchgate.net/publication/332029371_Possible_efficiency_boosting_of_non-fullerene_acceptor_solar_cell_using_device_simulation
Best wishes
This type of linear IV curve appears mainly due to the very low shunt. Yes very very high series also can do this. But from your structure it is unkikely to have such high series. I would rather suggest to deposit material uniformly as non uniform deposition can create leakage path even sometimes pinholes can be there in uniform deposition also which is responsible for very low shunt.
Dear Michael Kamel,
We used to work on P3HT:PCBM type of solar cells for number of years.
Firstly, there is a problem with your device structure. The Aluminium as a cathode doesn't form a good electron injection. Normally the insert layer of LiF (1 to 5nm)or Ca (20nm) between active layer and Aluminium. It forms good energy level alignment across the electron injection.
Secondly, since you don't use the encapsulation, the devices are degraded fast. What you could do is to use a sample chamber to connect a vacuum pump and generate an innert eenvironment.
Finally, the linear IV is likely to come from the property of a resistor. Your devices didn't work as a solar cell performance due to the above reasons.
Hope it helps.
All the best
Xuhua
Thank you dear colleagues and professors for all your comments.
Dear @Xuhua Wang, Can you please let me know what kind of sample chamber you mean? It would be great if you can send me an image to that.
In addition, I have seen in literature so many people using the same structure without electron transport layer. How can this work in my case?
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