At Intersolar conference in San Francisco, imomec, imec’s associated lab at the Hasselt University, and Solliance to present a CZTSe (Cu2ZnSnSe4)-based solar cell with 9.7 percent efficiency (1x1cm2, AM1.5G).
Imec explains: CZTSe is an emerging alternative solar cell absorber in thin-film solar cells, similar to CZTS (Cu2ZnSnS4). Unlike CIGS, CZTS and CZTSe do not suffer from abundancy issues. At 1.5-1.6eV for CZTS, and 0.9eV for CZTSe, their bandgaps make a combined material system ideal for a multi-junction, thin-film solar cell that rivals the efficiency of CIGS cells (about 20 percent). Imomec, imec and Solliance have defined a path towards further improving the layers and cell structures of CZTSe and CZTS absorbers aiming at developing a multi junction CZTS/CZTSe solar cell with 20 percent cell efficiency. The presented CZTSe solar cell is an important step forward to reach this goal.
CZTSe layers were fabricated by sputtering Cu, Zn and Sn metal layers on a Molybdenum-on-glass substrate and subsequent annealing in an H2Se containing atmosphere. 1µm thick polycrystalline absorber layers were processed into solar cells using a standard process flow for thin film solar cells and finished with a metal grid and anti-reflective coating. The solar PV cell measuring 1x1cm2 produced a maximum short circuit current of 38.9mA/cm2, an open circuit voltage of 0.41V and a fill factor of 61 percent.
“This is a big win for us. We’ve been working toward this milestone since 2011 when we first started our research on alternative materials for thin-film photovoltaics at imec/imomec,” said Marc Meuris, program manager Solliance of the alternative thin-film PV program. “Our efficiencies are the highest in Europe and approaching the world record for this type of thin-film solar cells, and we look forward to further advancing R&D to help bringing to market sustainable energy sources.”