Improvement in the conversion efficiency of single and double junction a-Si solar cells by using high quality p-SiO:H window layer and seed layer/thin n-μc-Si:H layer

The authors have developed high quality p-type amorphous and microcrystalline SiO:H films by the RF-PECVD method (13.56 MHz) at deposition conditions suitable for use in the fabrication of a-Si solar cells. Previously, they have developed seed layer/thin n-μc-Si:H bilayer which reduces significantly the minimum required thickness of n-μc-Si:H layer. By using these materials they have been able to improve the conversion efficiency of single and double junction (a-Si/a-Si) a-Si solar cells. For single junction cells (1.0 cm² ) the initial efficiency achieved to date is 11.6% (V_oc=0.91 V, J_sc=17.7 mA/cm² and F.F.=0.72). It is about 1% higher than that achieved with p-a-SiC:H as the window layer. For double junction cells, the initial efficiency achieved is 11.8% (V_oc=1.74 V, J_sc=8.9 mA/cm² and F.F.=0.76). There is further scope for achieving higher efficiencies by improving material characteristics and interfaces