More than 16% solar cells with a new 'HIT' (doped a-Si/nondoped a-Si/crystalline Si) structure

A HIT (heterojunction with intrinsic thin-layer) structure solar cell has been developed. In this structure, a nondoped a-Si thin layer was inserted between a p-type a-Si layer and an n-layer c-Si substrate. The open-circuit voltage and fill factor (FF) were significantly improved in these HIT structure solar cells compared with conventional p/n heterojunction solar cells. The improvement seems to originate in the reduction of backward current density. For higher efficiency, this HIT structure has been applied to textured substrates and achieved an efficiency of 18.1% (1 cm/sup 2/ cell). This efficiency is the highest value reported for a solar cell in which the junction was fabricated at a low temperature (120 degrees C). Application of this structure to the poly-Si thin film will yield a-Si/poly-Si thin-film solar cells of high efficiency.<
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