Researchers from Ulsan National Institute of Science and Technology (UNIST) in South Korea and the University of Pittsburgh in the U.S have reported a power conversion efficiency of 23.5% in a perovskite-silicon tandem solar cell by applying a special textured anti-reflective coating (ARC) polymeric film.
The team prepared the multifunctional film with phosphor particles measuring 10 μm in diameter. They are able to block ultraviolet (UV) light and silicon dioxide (SiO2) nanoparticles with a diameter of 10 nm to increase the ability of a perovskite-silicon tandem solar cell to absorb visible light. The scientists explained that the phosphors increase the reflectance of the ARC film, due to their large particle size, thus causing a backward light scattering issue. This in turn is compensated by the addition of the spherical SiO2 nanoparticles.
“Experimental and computational results show that SiO2 nanoparticles in the ARC film decrease the reflectance by increasing the diffuse transmittance,” they said, noting that the phosphor particles are able to absorb ultraviolet light with a wavelength of 380 nm and convert it into green visible light with a wavelength of 530 nm.
The film allowed the researchers to raise the efficiency of the solar cell by 4.5%. The cell was also able to retain 91% of its initial efficiency after 120 hours, while a reference device without the film only retained 50% of its efficiency after 20 hours.
“This optically engineered ARC film successfully promotes the light absorption of the perovskite/silicon tandem solar cell, leading to the improvement of power conversion efficiency of the tandem cell from 22.48% to 23.5%,” the scientists said.