A novel single junction thin film solar cell structure ITO/p-a-Si:H /i1-a-Si:H/i2-μc-Si:H/n-μc-Si:H/ITO is studied with Silvaco TCAD tool in this paper. The simulation data predicts that the thickness of the maximum conversion efficiency is between 250-500nm. For the best efficiency, the intrinsic μc-Si:H layer is predicted between 1500-2500nm. The results indicate the conversion efficiency is higher than that of the conventional amorphous silicon solar cell 7.53% and 8.14% for the conventional microcrystalline solar cells. To compare with the nanocrystalline (nc-Si:H) heterojunction thin film solar cell, the conversion efficiency of the proposed structure is increased more than 21.92%.