An attempt to improve the efficiency of the heterojunction p-a:C/n-Si has been made by introducing the highly insulating C-60 layer between the semiconductor layers of the cell structure. The conductivity of the implanted films is found to increase during the implantation process and it is attributed to the complete disintegration of the fullerene molecules. The efficiency of this structure is found to be 0.1% under AM 1.5 conditions which is ten times higher than the cell fabricated using the boron ion implanted fullerene without the insulating layer. (C) 2002 Elsevier Science B.V. All rights reserved.