Coloring solar cells with simultaneously high efficiency by low-index dielectric nanoparticles

Colorful solar cells are highly desired for photovoltaic integration with aesthetically appealing applications such as building facades, self-powered displays and other portable electronic devices. Structural colors by metallic or high-index dielectric nanostructures with judiciously tailored strong resonances are particularly appealing in engineering color appearances of solar cells. However, these prevailing schemes suffering from significant backward scattering power losses for coloration and large intrinsic dissipative losses inevitably degrade solar cell performances, representing a fundamental trade-off between coloring and efficiency improvement. Utilizing a different approach based on all-dielectric low-index submicron-sized spherical nanoparticles, we demonstrate a coloring strategy across the entire visible spectrum with simultaneously improved efficiency. Such nanoparticles exhibit ultra-broadband (300–1200 nm) and highly-directional forward scattering features due to the multipolar interferences. Integrating these nanoparticles atop silicon solar cells with an optical impedance matching layer modulates their optical reflection, leading to an extended complementary color palette with noticeable efficiency increase. To the best of our knowledge, this represents the first of its kind that solar cell efficiency can be increased when integrating with nanophotonic structures for coloring. The demonstration of wide coloring and simultaneous light trapping unlocks long-sought strategies to break the color-efficiency trade-off and opens new routes to advanced optoelectronic applications with multi-functionalities.