Potassium post deposition treatment of solution-processed kesterite solar cells

Publication date: Available online 5 November 2016
Source:Thin Solid Films
Author(s): S.G. Haass, M. Diethelm, C. Andres, Y.E. Romanyuk, A.N. Tiwari
Potassium post deposition treatment (K-PDT) has been a major breakthrough for CIGSSe (Cu(In,Ga)(S,Se)2) solar cells yielding world record efficiencies. K-PDT yields significant improvements in open circuit voltage, fill factor and CdS coverage leading to efficiencies above 20% for CIGSSe material. Here we present a similar K-PDT approach for solution processed kesterite solar cells. K-PDT improves the open circuit voltage of kesterite solar cells, however a severe blocking of the short circuit current and reduction of fill factor reduces the overall device efficiencies. Furthermore, quantum efficiency measurements indicate that K-PDT alters the properties of the CdS layer whereas time-resolved photoluminescence measurements exhibit an additional third exponential component, which can be attributed to minority carrier trapping at the interface.