SANYO Electric Co. Ltd. says it has broken its own record for the world's highest energy conversion efficiency in practical size (100 cm2 or more) crystalline silicon-type solar cells, achieving efficiency of 23.0% at a research level for its proprietary HIT solar photovoltaic cells.
The structure of the HIT solar cell allows a possible reduction in recombination loss of the electrical element (charged carrier) by surrounding the energy generation layer of single thin crystalline silicon (c-Si) with high-quality, ultra-thin amorphous silicon (a-Si) layers, the company notes.
SANYO recently improved the quality of the HIT solar cell junction through developing a technology for depositing a higher-quality a-Si layer over the c-Si substrate, while protecting the c-Si surface from being damaged. The result was an increase in the open-circuit voltage (Voc) from 0.725 V to 0.729 V.
In addition, the company reduced optical absorption loss in both the a-Si and transparent conductive layers. As a result, the short circuit current (Isc) improved from 39.2mA/cm2 to 39.5mA/cm2. SANYO also says it recently realized lower-resistance electrode material for use in the grid electrode and a higher aspect ratio through improving printing technology, leading to a success in reduction of resistance loss when an electric current flows through the grid electrode. As a result, the fill factor was improved from 0.791 to 0.80.