Boosting ultrathin aSi-H solar cells absorption through a nanoparticle cross-packed metasurface

•A nanostructure ITO with engraved crosses filled with 5 dielectric nanospheres.•This metasurface enhances optical absorption in an a-Si hydrogenated solar cell.•Mie resonant nanoparticles and crosses guide and confine light in active layer.•It reduces active layer thickness and degradation, improving charge extraction.•A simulation procedure achieves the best radius and refractive index of particles.