Using chemical wet-etching methods of textured AZO films on a-Si:H solar cells for efficient light trapping

Abstract

In this paper, Al-doped ZnO (AZO) films are deposited on glasses substrate by RF magnetron sputtering. The optical, electrical and morphological properties of AZO films textured by wet-etching with different etchants, H3PO4, HCl, and HNO3 are studied. It is found that the textured structure could enhance the light scattering and light trapping ability of amorphous silicon solar cells. The textured AZO film etched with HNO3 exhibits optimized optical properties (T% ≧ 80% over entire wavelength, haze ratio > 40% at 550 nm wavelength) and excellent electrical properties (ρ = 5.86 × 10−4 Ωcm). Scanning electron microscopy and Atomic force microscopy are used to observe surface morphology and average roughness of each textured AZO films. Finally, the textured AZO films etched by H3PO4, HCl and HNO3 were applied to front electrode layer for p–i–n amorphous silicon solar cells. The highest conversion efficiency of amorphous silicon solar cell fabricated on HNO3-etched AZO film was 7.08% with open-circuit voltage, short-circuit current density and fill factor of 895 mV, 14.92 mA/cm2 and 0.56, respectively. It shows a significantly enhancement in the short-circuit current density and conversion efficiency by 16.2% and 20.2%, respectively, compared with the solar cell fabricated on as-grown AZO film.