Ge-alloyed CZTSe thin film solar cell using molecular precursor adopting spray pyrolysis approach

Abstract

We report a promising fabrication approach for the synthesis of Ge-alloyed Cu₂Zn(Ge_xSn_1−x)Se₄ (CZGTSe) thin films using molecular precursors by spray pyrolysis to obtain band gap tuned kesterite solar cells. A stable and well dissolved precursor solution of CZTS/CZGTS with the desired elemental composition is prepared in DMSO solvent, sprayed on a Mo substrate and subsequently selenized under ambient selenium at high temperature to obtain well-crystallized absorber layers. The Ge-alloyed CZTSe thin films had improved surface morphology, grain size and crystal quality, which led to power conversion efficiencies as high as 4.72%. The growth properties and device analysis suggest that enhancement of the device performance can be achieved by further optimization of the absorber and interface layers with mitigation of defect activities.