Degradation evaluation of titanium dioxide under stress factors

Abstract

TiO2 is used in many sectors of industry such as health, food, defense, and energy. It is a well-known fact that TiO2 is especially used in applications in the field of organic hybrid solar cells (OHSC) as an electron transfer layer in the energy sector. However, the OHSCs have a degradation problem because of atmospheric stress factors such as laboratory atmosphere, prolonged light application (light soaking), and UV light. To understand the meta/instability problem in OHSC, it is required to be examined independently for each layer consisting of the solar cell. In this study, the TiO2 layer, widely used in OHSC applications, was grown on a rough glass substrate using a spin coating method. TiO2 layer was structurally and electrically characterized by XRD and photoconductivity methods respectively. TiO2 layer was characterized by exposure step by step to stress factors that are stated to cause electronic meta/instability in organic hybrid solar cells. Mobility-lifetime products were calculated from the flux-dependent photoconductivity and correlated with the electronic defects in the material due to stress factors. The findings in experiments show the laboratory atmosphere creates surface-related defects that can be eliminated by annealing. Light soaking, UV aging, and oxygen aging also create electronic defects associated with bandgap energy positions. These defects are partially eliminated with an annealing application.