In organic inorganic lead halide based solar cells, humidity seems to be a major factor.
Annealing at ambient hummidity level degrades the material to produce a yellow film (possibly PbO). I would like to know the reaction mechanism behind this.
How bad does working with a RH of 50 % affects the Perovskite solar cell? and will working at 25 % RH make any difference?
Does dipping the sample in Methyl ammonium iodide/IPA restore the material after degradation.
To my limited knowledge there are several possible degradation mechanisms possible and thinkable in PSC, depending on the specific device architecture and the materials involved.
First of all, the perovskite layer itself may degrade and decompose into, e.g. PbI2 as has been demonstrated by several groups already.
1) Qi Chen et al.: DOI:10.1021/nl501838y
2) Dualeh et al.: DOI: 10.1002/adfm.201304022
3) Supasai et al.: DOI: 10.1063/1.4826116
We could reproduce these results. The effect seems to be mainly thermally triggered, but might enhance through humidity.
Then there are a variety of thinkable degradation mechanisms for the rest of the PSC structure including all organic HTM, electron conductors and interfaces inbetween. Most noteworthy, with TiO2 as a good photocatalysts devices seem to be sensible to UV-light, for example.
Stability is still a rather challenging topic and no general agreement has been found on this yet, to my feeling.
All the best,
Paul Pistor
Thank you so much for your valuable information. I think it would quite an interesting study to analyze the degradation pathway in a controlled fashion. Thanks once again Nikhil and Paul.
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