Giraldo, S.; Neuschitzer, M.; Thers leff, T.; Lopez-Marino, S.; Sanchez, Y.; Xie, H.; Colina, M.; Placidi, M.; Pistor, P.; Izquierdo-Roca, V.; Leifer, K.; Perez-Rodriguez, A.; Saucedo, E. "Large Efficiency Improvement in Cu2ZnSnSe4 solar-energy-materials-and-systems Cells by Introducing a Superficial Ge Nanolayer" Advanced Energy Materials 5, 21, pp. - 2015 DOI: 10.1002/aenm.201501070