Dear Lethy kj

your question is not so clear, you must added some details about the structure of your PSC and the method you used to make the active layer and the hole transport layer.

You will need to add more details as the previous comment stated. It is common to see low Jsc and high FF for thinner devices which can be enhanced through several approaches. 

The device structure is ITO/PEDOTPSS/MAPbI/PC61BM/LiF/Ag. The active layer is made by a 1:1 molar ratio of MAI and PbI2 in DMSO GBL mixed solvent (3:7) volume ratio.

Have you verified the thickness of your active layer? Other way is to incorporate PbCl2 in a non stoichiometric ratio like this

PbI2:PbCl2:MAI = 1.3M:0.1M:1.3M

But once you put Chloride the annealing conditions need to be chosen very carefully. I would suggest 90C and annealing time = 5 mins to start with

Please see the attached pdf for reference.

Thank you so much Swaminathan for your answer. I haven't measured the thickness, but for a similar deposition recipe and precursor concentration it is around 260 nm. I would measure the thickness soon. 

Yesterday I tried the PbCl2 method (in the ratio PbI2:PbCl2:MAI = 1.26:0.14:1.3 M, but the same problem persists. In this case the FF is even better close to 78 (for the maximum PCE pixel = 3.5 %), but very poor Jsc (~ 4 mA/cm2). But I have used a annealing temperature of 100 for 20 minutes.  In the coming days I will try your suggestions.

Also, do you think, exposing the PbI2 and MAI to air can damage it?  The PbI2 and MAI were kept outside for sometime 

Have you ever tried spin coating the hot active solution? Also any idea how the filtering would affect the films? I am using 0.45 um PTFE filter. 

The same recipe (1:1 Molar ratio of PbI2 and MAI in DMSO and GBL was working well while I used to work in my previous group, but here I am struggling to reproduce it. 

Based on my knowledge, the big problem is the quality of the perovskite films. Please carefully check the crystallization of the perovksite film. Ag is not good. When you do the IV test, you scan from the negative voltage to the positive voltage or from the positive voltage to the negative voltage? That makes big difference. The scan rate and time delay also make different IV curves.

Thank you Zhang for your answer. The Jsc value don't change much with the voltage scanning direction (forward and reverse scan curves match). The same is true for scan rate. Would you please explain me about the time delay please?

Sorry for the delayed reply Lethy....

Welcome to the world of perovskite solar cells.Consistency seems to be one of the biggest problem.MAI and PbI2 both absorb moisture and will do so when exposed to air.Normally we dry the MAI and PbI2 in oven and then use it. The quality of MAI is very important. Different batches will give different results. How do you synthesize your MAI? Can you dry them and try fabricating again?

For the case of PbCl2 please try lower annealing temperatures and time.

Thank you Swaminathan for your answer. I do not synthesize my precursors, we buy them from Dyesol or Sigma Aldrich.  At what temperature you dry the powders? I can try to dry them using hotplate before making the precursor solution. This week I will try your suggestions and will update here

We normally dry them at 70C in a vacuum oven with dynamic vacuum. You can try to dry them in a glove box but it will not be as effective. 

Thank you so much Swaminathan, I will try this and update the result here. Also wills try whether I can dry them in a vacuum oven. 

Sure. You can contact me on [email protected] for any queries regarding cell fabrication.

That is a very kind help. I am struggling to reproduce my previous results. 

Dear Lethy kj,

I am facing the same issue as you mentioned in your question, I have tried the non stoichiometric ratio as per the paper mentioned by Swaminathan Venkatesan a member but cant get Jsc higher then 4~5mA/cm2.

here is the IV curve attached with this message, any suggestions from the group members?? flims looks really cool and the thickness is about 310nm for active layer.

Hi Ali Asgher Syed have you overcome your low Jsc problem with the perovskites?