Light trapping enhancement induced by bimetallic non-alloyed nanoparticles on a disordered subwavelength flexible thin film crystalline silicon substrate using metal-assisted chemical etching.

We report the application of gold and silver (AuAg) bimetallic non-alloyed nanoparticles (BNNPs) on disordered subwavelength structures (d-SWSs). The combined advantages of the plasmonic structures and d-SWSs improved the light trapping performance of flexible thin film crystalline silicon (c-Si) solar cells. Antireflective d-SWSs were fabricated using spin-coated Ag ink and subsequent metal-assisted chemical etching, which reduced the ion-induced surface damage produced by the dry etching process. The dimensions of the d-SWSs were finely tuned by adjusting the Ag ink ratio. Au8Ag8 BNNPs were employed on optimized d-SWSs to achieve low reflectance at broadband wavelengths. The Au8Ag8 BNNPs on the d-SWSs showed 180% and 145% enhanced absorption compared to bare c-Si film and Au8Ag8 BNNPs on c-Si film, respectively, in the wavelength range of 300-1100 nm. After 200 cycles of bending the antireflection of the structures remained similar to the original level. This study introduces new approaches for light management in flexible thin film c-Si solar cells over the broadband wavelength range.