This paper presents the light trapping effect by various front and back ZnO layers in silicon thin-film solar cells. The haze ratio in textured front ZnO layer does not have direct correlation with jsc. The μc-Si:H a...
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This paper presents the light trapping effect by various front and back ZnO layers in silicon thin-film solar cells. The haze ratio in textured front ZnO layer does not have direct correlation with jsc. The μc-Si:H and a-Si:H/μc-Si:H tandem solar cells prepared on textured ZnO:Al with small feature size (low haze ratio) give higher spectral response throughout whole wavelength range. The a-Si:H top cells act as a buffering layer between front textured ZnO and μc-Si:H layer. By this buffering effect, the carrier recombination by defects, observed in μC-Si:H single pin cells, is suppressed in a-Si:H/μc-Si:H tandem cells. As back reflection materials, doped and undoped ZnO layers with various thickness are incorporated with Ag back metal. In order to prevent reverse diode formation, thickness of undoped ZnO should be thin. However, this thin ZnO is not effective to improve light trapping by internal reflection of red/IR light. In case of doped ZnO, thinner layer gives higer red/IR response due to reduced free carrier absorption.
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