Imec and a group of photovoltaic companies have demonstrated a conversion efficiency of 23.3% on interdigitated back-contact (IBC) silicon solar cells.
It is part of the ongoing research in the industry aimed at increasing solar cell efficiency above the all-important 20% figure and also reducing the cost of solar power.
Interdigitated back contacts is a technique which is expected to increase the conversion efficiency of crystalline silicon solar cells and allow for further reduction of the cell thickness, simplification of module fabrication and improved aesthetics of the final solar cell modules.
Imec, together with its partners Schott Solar, Total, Photovoltech, GDF-SUEZ, Solland Solar, Kaneka and Dow Corning, have developed a high-efficiency baseline process for small-area IBC cells to increase the efficiency well above 20% and decreasing the cost of silicon solar cells.
“The results 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,” said Jef Poortmans, director of imec’s photovoltaic R&D programme.
Key aspects of the newly developed small-area (2x2 cm2) IBC Si solar cells are the n-type base float-zone (FZ) silicon substrates, a random pyramid texture, a boron diffused emitter, phosphorous diffused front- and back surface fields, a thermally grown silicon dioxide for surface passivation, a SiN single layer anti-reflective coating, lithography based patterning and Aluminum metallization.
The realized IBC cells achieve a designated area conversion efficiency of 23.3% (Jsc = 41.6 mA, Voc=696 mV, FF=80.4%), certified by ISE-Callabs.
According to Dr. Martin Heming, CEO of Schott Solar, the German solar manufacturer, teh research will allow it to acquire "important know-how and IP as basis for our next generation solar cell products”.
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