PERFORMANCE COMPARISON BETWEEN POLYCRYSTALLINE THIN-FILM AND SINGLE-CRYSTAL SOLAR-CELLS

Recent progress has increased the efficiency of polycrystalline thin-f ilm solar cells to roughly two-thirds that of single-crystal cells of comparable bandgap, The largest remaining difference is the excessive forward recombination current, which is larger by a factor of 20 for t he best CuInSe2-based cells, and by move than a factor of 100 for CdTe cells, Collection loss, related to diffusion length, is nearly as imp ortant for the CuInSe2-based cells. It is an open question how much ad ditional reduction in these two losses should be anticipated, However, other losses in thin-film cells due to window-layer absorption, refle ction and grid coverage will almost certainly be reduced so that effic iencies equal to 80% of crystalline counterparts should be a viable 5- year target.