Impact of Device Degradation on the Energetic Landscape in PM6:Y12 organic solar cells

Date

Jan 29, 2025

Time

10:20 AM - 11:20 AM

Speaker

Bekcy Joseph

Affiliation

IFW Dresden

Language

en

Main Topic

Materialien

Host

Ines Firlle

Description

Organic photovoltaic (OPV) devices have surpassed 19% power conversion efficiencies, marking significant progress in their development. Despite these promising advances, stability remains a major challenge that has to be addressed before commercialization. These devices' fundamental processes, such as charge generation, recombination, or transport, depend on the organic materials' electronic structure and the energetic alignment with the other device layers. Hence, understanding the impact of degradation on the energetics of OPV devices is essential for improving their long-term performance. Ultraviolet photoemission spectroscopy (UPS) has been widely employed to investigate the electronic structure of organic materials, but its surface sensitivity limits its application for the study of energetics in the bulk and at buried interfaces of organic solar cells. Recently, we have developed a novel spectroscopic approach – UPS depth profiling – in which UPS is combined with argon cluster etching to enable the direct probing of the energetic landscape of OPV devices. In this study, UPS depth profiling was used to investigate the origin of the performance loss of PM6:Y12 solar cells upon continuous illumination at 1 sun. Mapping the energetics in pristine and aged active layers revealed that the energy levels of the active layer evolve upon aging, resulting in a decrease in the driving force for change separation. These studies were complemented by transient absorption spectroscopy measurements showing reduced charge generation efficiency in aged devices. These studies provide new insights into the degradation mechanisms of OPVs, important for the future development of mitigation strategies.

Links

• Seminars at the IFW

Last modified: Jan 29, 2025, 7:39:36 AM