Development of solar cells based on heterojunction of amorphous silicon and crystalline silicon (HAC): HIT and post HIT
Lang Zhou Haibin Huang
Abstract: HAC-based solar cells by nature have advantages of higher voltage, lower temperature coefficiency, higher sensitivity to weak irradiation, LID-free and PID-free. HIT structured HAC cells have been a great success over 20 years. Commercial production of HIT-type solar cells grows rapidly in China in the recent 2 years, reaching about 2GWp/a in production capacity and 23% in efficiency of energy conversion. The fast rising of the efficiency in commercial production scale is impressive, indicating strength of this technology.
However, the structure of HIT cells is far from perfect. Among quite a few drawbacks, its front surface light adsorption is regretfully too much, leading to the fact that its current density output is even less than conventional BSF cells. A modified design, HAC with diffused front surface field, HACD, which is relatively close to commercialization, is proposed and theoretically justified by computation. Preliminary experiment was carried out, and a processing recipe is proposed.
Furthermore, a more complicated structure aiming for even higher efficiency and lower cost, HAC with localized pn junction, HACL, is proposed and supported by computation. Its processing recipe, however, is not figured out yet and remains open to the HAC circles.
A brief introduction about the IPV at NCU will be included.