en.Wedoany.com Reported - Researchers at the Helmholtz-Zentrum Berlin (HZB) in Germany have used perovskite materials to create a highly complex "triple-junction" solar cell, achieving a conversion efficiency of 27.3% with no performance degradation after 770 hours of continuous operation.

Silicon solar panels have long dominated the market but are approaching their physical efficiency limits. Perovskite materials have become a research hotspot due to their low cost, light weight, and ability to be mounted on flexible substrates. By stacking three perovskite absorber layers with different bandgaps, this cell can collect more sunlight than silicon panels.

The weakness of conventional perovskite cells lies in the polymer layer (PEDOT:PSS) used for charge transport between sub-cells, which has low light absorption efficiency and is prone to decomposition. The research team attempted to replace this polymer with a self-assembled monolayer (SAM). Initially, the SAM layer could not effectively transport charges. Co-first author and postdoctoral researcher Yeonghun Yun explained: "Therefore, we added an additional layer beneath the SAM as a substrate." The team placed an ultrathin graphene oxide (GO) layer directly under the SAM. This GO/SAM bilayer structure altered the interface properties, achieving perfect morphological and electronic matching, enabling smoother charge transport and significantly reducing optical losses.

The new triple-junction solar cell achieved a power conversion efficiency of 27.3%, among the highest levels in this technology field. Cells equipped with the GO/SAM layer maintained over 90% of their initial performance after 770 hours of continuous operation, demonstrating excellent durability. The research team noted that tin-lead-based perovskite layers are highly susceptible to oxidative degradation when exposed to oxygen and moisture, and the hermetic chemical barrier formed by the GO/SAM bilayer effectively protects the fragile tin layer from environmental damage.

Professor Steve Albrecht, head of the HZB Perovskite Tandem Solar Cell Department, stated that by improving individual perovskite films, the efficiency of this lightweight structure could easily exceed 30%. The research findings were published in the journal Joule on July 9.