Pushing the boundaries of conventional silicon solar cell technology, while offering a low-cost production approach, took another step forward, according to R&D organisation, imec. In conjunction with its industrial affiliates, researchers have developed a small-area (2×2 cm2) – interdigitated back-contact (IBC) silicon solar cells that has demonstrated a conversion efficiency of 23.3%. Work will now focus on developing a large-area and production viable cell and process steps.
Jef Poortmans, director of imec’s photovoltaic R&D program commented: “We are delighted to demonstrate these excellent efficiency results on IBC silicon solar cells. They prove the relevance of the IBC technology to our industrial partners. Such high efficiencies on small-area IBC silicon solar cells are a perfect base for further developing a large-area and industrially feasible IBC cell technology at imec.”
Imec noted that it used an n-type base float-zone (FZ) silicon substrate coupled to an array carefully selected process steps. A wet chemical random pyramid textured surface was employed, followed by a boron diffused emitter, phosphorous diffused front- and back surface fields, a thermally grown silicon dioxide for surface passivation, and a SiN single layer anti-reflective coating were used.
Interestingly, imec said it used a lithography tool, used extensively in the semiconductor industry for patterning to determine the different contacts at the backside for aluminum metallization. Imec told PV-Tech that it was working in parallel to develop a ‘litho-free’ solution to further reduce cost for commercial adoption.
According to imec, the advanced IBC cell achieved a designated area conversion efficiency of 23.3% (Jsc = 41.6 mA, Voc=696 mV, FF=80.4%), certified by ISE-Callabs.
Imec’s silicon photovoltaic industrial affiliation program partners include, Schott Solar, Total, Photovoltech, GDF-SUEZ, Solland Solar, Kaneka and Dow Corning.