Nanoscale Property Enhancement of Photovoltaic and 2D Layered Magnetic Materials

Abstract

Three materials were investigated using two variations of atomic force microscopy and other characterisation techniques. CZTSSe is an earth abundant, non-toxic, semiconductor. Na is often doped into the kesterite structure to improve grain size and overall efficiency. In this thesis Na and other elements are found to migrate in the solar absorber material post deposition. The Na moves preferentially through the grain boundaries, and by applying an external voltage using two capacitor plates, device efficiency is found to be enhanced. The second material investigated is 2D layered perovskite samples BA2Pb(I/Br)4. Using similar external voltage application, nanosized structures form on the surface of the Iodine containing samples. These structures were investigated and found to be highly oriented perovskite structures that enhance crystallinity and conduction attributes. The final material investigated is CGT, a 2D layered magnetic material with a curie temperature of 61K. This material was investigated using a cryogenic MFM system. CGT samples were mechanically buckled forming folds in the 2D sheets. These folds have highly strained areas that were found to show a magnetic contrast at temperatures well above the unstrained curie temperature of 61K. In some samples the enhanced magnetic signal was found even at room temperature, offering future room temperature applicative avenues