Researchers are in the race to make new, better, and more efficient solar cells. In one such attempt, scientists developed a 24.2% efficient POLO back junction solar cell built with PECVD.

The team from Institute for Solar Energy Research Hamelin (ISFH) and German PV equipment manufacturer Centrotherm worked together. They have developed highly efficient n+-type polysilicon on oxide (POLO) back junction solar cells. For this, an industrial plasma-enhanced chemical vapor deposition (PECVD) system with a low-frequency plasma source was used. The device achieved a slightly higher efficiency than the reference device fabricated through more expensive atomic layer deposition (ALD). Scientists used an industrial batch-type LF-PECVD system by Centrotherm to deposit the AIOx layer.

The lead author of the study, Byungsul Min said, “Our study shows for the first time an effective industrial cleaning and passivation for the undiffused textured front side with excellent passivation quality. Especially, the AlOx/SiNy passivation layer stack is fabricated with an industrial plasma enhanced chemical vapor deposition (PECVD) system with a low-frequency (LF) plasma source which is much more cost-effective than atomic layer deposition (ALD) systems or PECVD systems with a high-frequency (HF) plasma source.”

Highlights

  • The POLO back junction solar cell doped in Czochralski-grown silicon wafer measures 156.75 mm x 156.75 mm.
  • The resistivity of the silicon wafer is 0.73 Ωcm.
  • The POLO cell achieved: power conversion/efficiency (24.2%), short-circuit current density (40.2 mA/cm2), fill factor (83.0%), and open circuit voltage (725 mV). These results were confirmed by ISFH CalTeC.
  • Another device on a textured gallium-doped Czochralski-grown wafer with a resistivity of 0.9 Ωcm. It has a 10 nm thick layer of AIOx deposited by ALD and a SiN y layer.
  • This device achieved: efficiency (24.1%), short-circuit current density (39.9 mA/cm2), fill factor (83.2%), and open circuit voltage (725 mV).

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According to the researchers, “The integration of this passivation sequence into our current process flow for POLO BJ solar cells has been successfully demonstrated with POLO BJ solar cells, which show even higher cell efficiencies than the reference fabricated with lab-scale processes.”

Source: 24.2% efficient POLO back junction solar cell with an AlOx/SiNy

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Elliot is a passionate environmentalist and blogger who has dedicated his life to spreading awareness about conservation, green energy, and renewable energy. With a background in environmental science, he has a deep understanding of the issues facing our planet and is committed to educating others on how they can make a difference.

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