Why Does the Forward Scan Show Lower Efficiency in Perovskite Solar Cells?

[Mayan Fung]

TL;DR

Why does the forward and reverse J-V scan of a perovskite solar cell is different?

Hi all, I am working on perovskite solar cell related studies. J-V curve (current density-voltage curve) is one of the important measurements to determine the performance of the device. In practice, we perform the reverse scan first then then followed by the forward scan. There is usually a difference in the curve (worse in the forward scan) which we called hysteresis due to some defects and shortcomings of perovskite.

However, even if I don't perform the reverse scan first (i.e. I directly perform the forward scan), the forward scan still shows a worse efficiency than the reverse one. What is the reason?

 

[Baluncore]

The cells are being changed by the order of initial testing. That suggests the formation process has not been completed and the chemistry is still unstable. You need to experiment to find the testing sequence that produces the most efficient and stable cell.

We would need to know more about the fabrication process you use, what light exposure occurs and how you perform the scans, to identify what the changes in the material and performance might be.

https://en.wikipedia.org/wiki/Perovskite_solar_cell#Stability

 

[Enigman]

Reverse scan always gives better PCE in PSCs. Things generally blamed are:

1. Ferroelectric polarization

2. Ion migration

3. Charge trapping

4. Capacitive effects

I would give this a read: https://www.sciencedirect.com/science/article/pii/S0927024816301933?via=ihub