Dear Ehsan, in order to resolve the problem partially, it is advisable to measure the photocurrent by measuring the illuminated I-V at reverse bias starting from zero volt down ward to any negative voltage sufficient to saturate the solar cell current.

Here the short circuit current is smaller than the photo current. Most probable ,the main problem in this cell is the high resistance of the contact interface between the active material and the metal electrodes. such that the collection process of the electrons and holes will be impeded.

SPECIFICALLY YOU DO NOT HAVE ELECTRON TRANSPORT LAYER BETWEEN THE ACTIVE LAYER AND Al. AlSO, THERE IS PROBLEM WITH THE STABILITY OF PEDOT-PSS ON ITO.

For more information please see the link:http://pubs.rsc.org/en/content/articlehtml/2012/jm/c2jm35646e

wish you success

In the single diode model, your series resistance seems to be about 110 ohms. Your photocurrent generator produces 0.23V under no load, which means that your Isc will be at very roughly 2.5 x 110 x 1e-3 volts. Which it is!

Thank you Toni. But this device is suppose to be regular opv with voc ~0.6 and Jsc~10 mA. What could bethe problem to cause this low performance?

Dear Ehsan, in order to resolve the problem partially, it is advisable to measure the photocurrent by measuring the illuminated I-V at reverse bias starting from zero volt down ward to any negative voltage sufficient to saturate the solar cell current.

Here the short circuit current is smaller than the photo current. Most probable ,the main problem in this cell is the high resistance of the contact interface between the active material and the metal electrodes. such that the collection process of the electrons and holes will be impeded.

SPECIFICALLY YOU DO NOT HAVE ELECTRON TRANSPORT LAYER BETWEEN THE ACTIVE LAYER AND Al. AlSO, THERE IS PROBLEM WITH THE STABILITY OF PEDOT-PSS ON ITO.

For more information please see the link:http://pubs.rsc.org/en/content/articlehtml/2012/jm/c2jm35646e

wish you success

Thanks you Abdelhakim For the advice. I was also suspicious about ITO and Al contact. I am using non patterned ITO glass. How important using a patterned ITO is? 

Welcome Ehsan,

I think it is more common to use inverted inverted device structure where the ITO is contacted by ETL which are types of conduction transparent oxides and then comes the active organic bilayer followed by the HTL and the metal electrode.

For more information please follow the link:http://www.sciencedirect.com/science/article/pii/S0079670013000427

In the literature it is found that the ito layer can be patterned with a buffer layer to stabilize it against the pedot. You may find more information in the link:https://www.researchgate.net/profile/Martijn_Wienk/publication/234033689_Fabrication_of_PEDOT-OTS-patterned_ITO_substrates/links/00b4952bf

wish you success

Article Fabrication of PEDOT-OTS-patterned ITO substrates

Maybe this is amorphous Si on glass?

Some time ago I tried to select 3 samples of amorphous Si with similar I(V) curves.  I had test 10 samples without success. Every sample has it's own slope. But Isc and Voc are similar.

The crystaline Si I(V) curves are more reproducible.

https://www.researchgate.net/post/Who_know_the_suitable_SPICE-model_for_Amorphous_Silicon_PV-battery

Thank you Vladimir. Curves are for organic solar cell with ITO/PEDOT:PSS/P3HT:PCBM/Al

I suggest inserting a ETL layer between the active layer and Al electrode. That would make the top contact more ohmic. Also depending on the evaporation rate of the Al electrode, Al metal can diffuse to your active layer and can create shunt paths reducing the Voc of your devices. You can insert either Ca or LiF or ZnO nanoparticle layer to resolve this issue.

Sometimes thermal annealing the completed devices (ITO/PEDOT:PSS/active layer/Al ) inside the Glovebox at 120-140 degC for around 10 minutes can also help to improve the device performance as this will make the contact between the Activelayer and Al more intact. 

Thanks Lethy. I will try both. Is there any preference between Ca or LiF?

LiF needs fine control, with a thickness restriction of 1 nm as it is insulator.  Ca would be more easy to start with.

Try to change the value of shunt and series resistance.

Any explanation for this type of curve?