I fabricated a 1.25 eV n-i-p perovskite solar cell, surprisingly i got almost zero photo current, in the same batch i tried a 1.6 eV perovskite solar cell , i got 16% power conversion efficiency? can anyone tell me what might went wrong with my devices ? I also went through some literatures, i found only a few number of people worked on low band tin based perovskite. what might be the possible reasons for this ?
May be due to some fabrication procedure but an optimized band gap is used . It will be better if you use both. Read some attached articles where low band gap lead hallide absorbing layers showing a high Jsc.
If you obtain almost zero photocurrent means that:
-Your material absorbs the incident radiation very little,
This means that the material has very low absorption coefficent.
- You material has appreciable absorption coefficient and it contains many defects acting as a very effective recombination centers.
- The HTL will not extract holes from the pervoskite before they recombine because it is not energetically matched with the perovslite material. The same can happen with the ETL it may be match not matched with the perovskite layer. It is so that condcution band edge of the HTL must lie above that of the perovskite and conduction edge must lie above that of the perovskite. Similar reasoning can be applied to the ETL. which must attract the electrons and reject the holes.
Best wishes
I was more concerned with the device architecture, same perovskite worked with P-i-N structure not worked with the N-i-P structure, provided that all HTL, ETL fulfills the energy alignment in both cases. Is this a minor issue or some major issue is there ?
How is the dark i-v characteristics. It must show good rectifying i-v characteristics. How is the properties of the low energy gap perovskite in addition to the energy gap of 1. 25 eV. What is about the minority carrier life time in the bulk of the materials. In heterojunction solar cells of such structures the recombination at the interface may be high.
When you answer these questions you will get the cause of very low shortcircuit current.
Best wishes
I’havent yet characterized it fully . I will try to get information of those parameters . Thank you very much for your kind response . Appreciated !
Dear Nabin Ghimire ,
The cause may be that deposition of the active perovskite layer on one material is much better than the other. In the sense it grows with smaller defects which can act as recombination centers. The deposition conditions and the substrates has a profound effect on the structure of the deposited film.
You can easily check this by measuring the life time of minority carriers!
To make such characterization please refer to the paper:Article A distributed SPICE-model of a solar cell
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