By Cameron Chai
Imec and collaborators have demonstrated interdigitated back-contact silicon solar cells that have a high conversion efficiency of 23.3%. Schott Solar, Solland Solar, GDF-SUEZ, Dow Corning, Kaneka, Photovoltech and Total are imec’s partners in the silicon photovoltaic industrial affiliation program.
Interdigitated back-contact silicon solar cells above 23% efficiency
Interdigitated back contacts are designed to reduce the cell thickness of crystalline silicon solar cells and also improve their efficiency of energy conversion. The contacts will also help simplify the module fabrication and further improve the artistic looks of the solar cell modules.
Imec aims to reduce the cost of silicon solar cells and also increase their efficiency through their partner affiliation program. It has collaboratively developed an efficient baseline process for IBC Si cells with a small area of 2 x 2 sq. cm. These cells have a random pyramid texture, phosphorous diffused surface fields for both the front- and back, and silicon substrates of n-type base float-zone types. They also feature single layer SiN anti-reflective coating, aluminum metallization, lithography-based patterning, a boron diffused emitter, and silicon dioxide for surface passivation that is thermally grown. The resultant IBC solar cells have achieved 23.3% area conversion efficiency consisting of 41.6 mA Jsc, 696 mV Voc and 80.4% FF. The efficiency has been certified by ISE-Callabs.
Imec’s photovoltaic R&D program director, Jef Poortmans, stated that the high efficiencies achieved on small-area solar cells are a base for developing industrially feasible and large-area IBC cell technology.
SCHOTT Solar’s CEO, Dr. Martin Heming, stated that the results of the test confirmed the company’s confidence in imec’s R&D capabilities. The program allowed the company to gain critical knowledge and IP, which will serve as the basis for its future products, he added.