Imec’s Solar Cells Have 23% Efficiency

Silicon solar cells can achieve a better than 20% efficiency using a technology called IBC (interdigitated back-contact). A group led by Imec have demonstrated 23.3% efficiency on a small-area cell.

“The results prove the relevance of the IBC technology to our industrial partners,” says Jef Poortmans, director of Imec’s photovoltaic R&D programme, “such high efficiencies on small-area IBC silicon solar cells are a perfect base for further developing a large-area and industrially feasible IBC cell technology at Imec,”

Imec’s  industrial partners in the IBC research are: Schott Solar, Total, Photovoltech, GDF-SUEZ, Solland Solar, Kaneka and Dow Corning.


IBC should reduce cell thickness, simplify module fabrication and improve the look of solar cell modules.


Key aspects of the 2×2 cm2  IBC cells are the n-type base float-zone (FZ) silicon substrates, a random pyramid texture, a boron diffused emitter, phosphorous diffused front- and back surface fields, a thermally grown silicon dioxide for surface passivation, a SiN single layer anti-reflective coating, lithography based patterning and Aluminum metallization.



  1. The British councils must do much more to support Photovoltaics in the United Kingdom as they have already been tinkering with the F-I-T making it less appealing for owners to install solar to their homes.

  2. First they said it has a 24.2% efficiency, then 33% and now 42.8%. What’s the truth behind these numbers really?

  3. Ah Mr C, now I understand. When I was inquiring about solar power, the panels from one company were down to 80% after 25 years. I’d imagine that there could be quite a bit of variability in lifetime.

  4. Keith, an apology, I did not mean to project on efficiencies for future designs of solar cells.
    What I tried to imply was that solar cells degrade over time and that their efficiency drops, you might buy them with 23% now but they will be more like 18.4 in 5 years’ time?

  5. Mark, the figure I quoted is for single junction single cell silicon cells from the Shockley-Queisser limit.
    Of course you can get more than this from fancy structures using multiple junctions, but of course these cost more and until the cost per watt declines they will remain in the lab.

  6. Well these guys were claiming 42.8% a few years ago;
    Not a commercial product but easily above 33%.

  7. Maximum theoretical efficiency of a single junction silicon solar cell is about 33%, Mr C.

  8. “and improve the look of solar cell modules.”
    “a random pyramid texture” and “phosphorous diffused front- and back surface fields” do sound very pretty….

  9. The key question is what will be the efficiency in 10,15,20 and 25 years?

  10. This is a nice result for catching up. However, Sunpower already has large area (125x125mm²) devices of this type with 24.2% efficiency. And they are not on expensive float-zone material, but standard PV-Gradee CZ-silicon.

  11. wow that’s amazing your only 2 percentage points and 3 years behind the Aussies, sounds a bit like the English cricket team…

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