Bandgap value is one of the vital parameters to evaluate the solar cell performance, which should close to Shockley-Quiser limit. The single junction solar cell get to its maximum (~33%) at 1.4eV. If just compare the value of bandgap, perovskite bandgap is closer to the SQ limit. Of course, the perovskite structure with the distinct Pb-I bonding renders this type of materials unique properties, such as large absorption with thin layer, direct bandgap with less recombination loss, extra high lifetime of carriers, etc. For understanding more, I recommend to read several review papers on this field.

Thank you Xixia Liu

https://phys.org/news/2018-04-perovskite-solar-cells-efficient.html

Strong solar absorption , low non-radiative carrier recombination rates and a reasonably high carrier mobility are main reasons.

Jan Schmidt is right. While it is ture that there was a huge progress in efficiency of perovskite cells over the last years, they are not more efficient than Si solar cells.

To be seen if they will surpass Si solar cell efficiency in the future.

I agree with Jan Schmidt and Jan Haschke. I believe the main advantage of perovskite based solar cells over current technologies is not a higher efficiency, but lower production costs.

Thank you Daniel Gau , Jan Schmidt and Jan Haschke for your valuable insights.

Yes, even I found Perovskites to be less useful than Silicon. mainly due to their low stability issues. But easy fabrication is main advantage of these cells

Shrikant Chavan I never said that Perovskite-based solar cells would be less usefull than Silicon-based ones.

In terms of market share over the next 10 years, however, I believe that perovskite will not be a "major player".

The perovskite solar cells has yet to pass long way before they can compete with the single crystal solar cells. Even if they appraoch the photo conversion efficiency of silicon they suffer from aging effects which is an important issue for solar cells as they are used under hard environmental conditions. The major advantage of the pervoskite solar cells is their extremely thin film structure rendering them cheaper for production.

Additionally , there are tremendous research effort to produce low cost high efficiency single crystal solar cells by developing the thin film single crystal Si solar cells using heterojunctions and surface passivation together with photonic crystals as optical matching layer at the surface of the silicon.

Such solar cells will inherit the long time stability and the long lifetime of silicon. With the new junction , passivation and photonic techniques these thin Si solar cells will reach the recorded high efficiency of wafer based single crystal solar Si solar cells.

Best wishes

I agree with Jan Schmidt. Achieving crystalline silicon cells with efficiencies exceeding 27% is definitely possible during the years ahead. Reducing surface recombination by using passivated contact is one of the key ingredient to reach this goal. The other way out is to reduce bulk recombination by reducing the bulk silicon thickness. However, the short circuit current can suffer unless an efficient light-trapping strategy is not used. Recently, we have shown that using very efficient light-trapping using photonic crystal, one can achieve 28-29% conversion efficiency with just 10 micron thick silicon (advantages are: low cost due to usage of lesser silicon, flexible due to ultra-thin architecture). You may refer to: Article Designing High-Efficiency Thin Silicon Solar Cells Using Par...

Sayak Bhattacharya Thank you sir

Just a short note to Jan Schmidt comment: The certified efficiency of perovskite solar cells is now 23.3% (the updated NREL chart).

Shrikant Chavan back to your question, as you can already see from the comments made earlier, PSCs are behind Silicon PV devices in terms of efficiency, and might not easily reach further closer! You have to understand that it is partly due to 'dirty' processing of perovskite materials, unlike silicon. I believe it is not wise to compare the both technologies as they both are useful in their diverse application domains. You can refer to our review (Article Progress, challenges and perspectives in flexible perovskite...

Direct band gap makes perovskite tollerate shorter diffusion length - a reason possible.

Dear Chavan,

I agree with all the answersby the people for the question that you have raised. I would like to add some more points.

# Although the CH3NH3PbI3 has higher bandgap of 1.55 Vas compared to silicon 1.11 eV.

If we look at the forbidden gap (Eg) of these materials, Si is having Eg of 1.1 eV . So, its obvious that Si will show better photovoltaic performance due to extending light absorption of low energy photons. But here , we have to look on what is "the fundamental loss in energy (FLS)" , in other words over potential required for the charge injection and hole regeneration, for these solar cells. For eg. the maximum Voc can be derived from Si solar cells is limited to ~0.6 V, but its Eg is 1.1V, almost 0.5 V is lost , or it is expended for charge injection and hole regeneration as over potential. But in the case of Perovskite solar cells, The Voc is ~1.2 V and hence, FLS = 1.5-1.2=0.3 V. therefore, the overpotential required for the above mentioned two processes is minimum (0.3 V)for the case of perovskite solar cells. This is the main reason for why perovskite solar cells show superior photovoltaic performances than other existing solar cell technologies.

Hope this explanation will be helpful to you.

Regards

Anand.

Anantharaj Gopalraman: "For eg. the maximum Voc can be derived from Si solar cells is limited to ~0.6 V, ..."

I'm not sure how you mean this; could you provide a more detailed explanation for this aspect?

Jan-Martin Wagner I meant in a way that the fundamental loss in energy (injection and regeneration) is high as far as concerning Silicon solar cells. Single crystal solar cells have Voc of around ~730 mV and polycrystalline Si solar cells have 600 mV. Please go through the review article (figure 2), you will get detailed explanation. (J. Phys. Chem. Lett., 2013, 4, 3623-3630)

Regards,

Anand

Thanks for the reference! So you refer to the actual performance of silicon solar cells, not to some fundamental material property (well, at least not directly).

Dear Azhar Fakharuddin - Could you please send me a copy of your Review Article: Pregress, Challenges and Perspectives in Flexible Perovskite Solar Cells?

I feel the most important reason for the "superior" performance of the perovskite MAPbI3 is that it has much less detrimental defects compared to the other prominent materials. Please see this manuscript that makes the first objective side-by-side comparison between high quality GaAs, CdTe, and MAPbI3, over multiple optolectronic properties pertinent to good PV performance.

Preprint Comparative studies of optoelectrical properties of prominen...

BTW, diffusion length is not the longer the better in a solar cell. See the discussion in the above manuscript.