Reduction of the plasmonic absorption in the nanotextured back contact of a-Si:H solar cells by employing an n-SiOx:H/LiF interlayer

We have developed a hydrogenated n-type silicon oxide (n-SiOx:H)/lithium fluoride (LiF) interlayer for effective light trapping in pin-type hydrogenated amorphous silicon (a-Si:H)-based solar cells with a 200-nm thick intrinsic a-Si:H absorber. The spectral response of the fabricated solar cell is clearly enhanced in the wide wavelength range of 500-750 nm because of the reduced plasmonic absorption in the nanotextured metal back contact and effective refractive index grading. The surface morphology of the back contact is effectively smoothened by the insertion of the ultrathin (2.1 nm) LiF interlayer. As a result, the short-circuit current is improved by 10.7% from 13.1 to 14.5 mA/cm2. Consequently, we have achieved a conversion efficiency of 9.0%.