Application of i-a-Si1−xOx:H as i/n interface layer of a-Si1−xGex:H single-junction flexible solar cell

Abstract

We investigated the effect of the flow rate of CO2 on the optical and structural properties of i-a-Si1−xOx:H films deposited using 27-MHz very-high-frequency plasma-enhanced chemical vapor deposition. Experimental results show that with an increasing CO2 flow rate, the optical bandgap of the film was increased due to the increase of the oxygen concentration, while the transparent result showed a higher value than the conventional a-Si:H material at long wavelength. This result indicated that the i-a-Si1−xOx:H is suitable for an application to the i/n interface layer of an a-Si1−xGex:H solar cell. The deposition conditions of the films were applied to the i/n interface layer of a-Si1−xGex:H single-junction flexible solar cells. It was found that the conversion efficiency of a solar cell with an i-a-Si1−xOx:H i/n interface layer showed a higher value due to the higher short circuit current density compared to a conventional a-Si:H i/n interface layer. In addition, with the optimum conditions of the i-a-Si1−xOx:H i/n interface layer, a conversion efficiency of 6.6% (Voc = 0.81 V, Jsc = 14.6 mA/cm2, and FF = 0.57) was achieved with a solar cell area of 1 × 1 cm2.