Electronic transport, ionic activation energy and trapping phenomena in a polymer-hybrid halide perovskite composite

Abstract

The exploitation of methylammonium lead iodide perovskite-polymer composites is a promising strategy for the preparation of photoactive thin layers for solar cells. The preparation of these composites is a simple fabrication method with improved moisture stability when compared to that of pristine perovskite films. To deepen the understanding of the charge transport properties of these films, we investigated charge carrier mobility, traps, and ion migration. For this purpose, we applied a combinatory measurement approach that proves how such composites can still retain an ambipolar charge transport nature and the same mobility values of the related perovskite. Furthermore, thermally stimulated current measurements revealed that the polymer influenced the creation of additional defects during film formation without affecting charge mobility. Finally, impedance spectroscopy measurements suggested the addition of starch may hinder ion migration, which would require larger activation energies to move ions in composite films. These results pave the way for new strategies of polymer-assisted perovskite film development.