Low band gap liquid-processed CZTSe solar cell with 10.1% efficiency

A low band gap liquid-processed Cu2ZnSn(Se1-xS x)4 (CZTSSe) kesterite solar cell with x ≈ 0.03 is prepared from earth abundant metals, yielding 10.1% power conversion efficiency. This champion cell shows a band gap of 1.04 eV, higher minority-carrier lifetime, lower series resistance and lower Voc deficit compared to our previously reported higher band gap (Eg = 1.15 eV; x ≈ 0.4) cell with similar record efficiency. The ability to vary the CZTSSe band gap using sulfur content (i.e., varying x) facilitates the examination of factors limiting performance in the current generation of CZTSSe devices, as part of the thrust to achieve operational parity with CdTe and Cu(In,Ga)(S,Se)2 (CIGSSe) analogs. © 2012 The Royal Society of Chemistry.