AL2O3 ANTI-REFLECTION LAYER AT GLASS/ZNO:AL INTERFACE FOR ENHANCEMENT OF LIGHT TRAPPING IN SILICON THIN FILM SOLAR CELLS

摘要

Al_2O_3 anti-reflection layer (ARL) was proposed at glass/transparent conducting oxide (TCO) in order to decrease optical reflection and increase optical absorption in silicon (Si) thin film solar cells. Optical simulation results showed that Al_2O_3 thin film inserted at the glass/TCO interface can decrease the reflectance of microcrystalline (μc-Si:H) thin film solar cells. The reflectance was minimized by employing the Al_2O_3 ARL with a thickness of ~ 40 nm. The refractive index of sputter-deposited Al_2O_3 thin film was about 1.69 at a wavelength of 550 nm, which was very close to the theoretical optimum value of about 1.67 for minimizing the optical reflectance. The reflectance of fabricated μc-Si:H solar cells was decreased with the Al_2O_3 ARL in the overall wavelength regions. In addition, quantum efficiency was improved in the solar cells with the Al_2O_3 ARL. The J_(sc) was increased from 22.7 to 23.5 mA/cm~2 without sacrificing V_(oc) or FF. The efficient light trapping effect of the Al_2O_3 ARL was experimentally demonstrated in our experiment.