Solliance, imec Achieve 9.7 Percent Efficiency with New Thin-Film CZTSe Solar Cell

At the Intersolar conference in San Francisco, imomec, imec’s associated lab at the Hasselt University, and Solliance, the European R&D consortium that focuses on thin-film photovoltaic solar energy (PV), will present a CZTSe (Cu2ZnSnSe4)-based solar cell with 9.7% efficiency (1x1cm2, AM1.5G). This promising result is an important step bringing the solar industry closer to a sustainable alternative for the highest efficiency thin-film solar cells in production, based on CIGS (Cu(In,Ga)(S,Se)2).

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%). 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% cell efficiency. The presented CZTSe solar cell is an important step forward to reach this goal.

Imec/imomec fabricated the CZTSe layers by sputtering Cu, Zn and Sn metal layers on a molybdenum-on-glass substrate and subsequent annealing in an H2Se containing atmosphere, achieving 9.7 percent efficiency.

“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.”