Spectroscopic identification of defects in materials for perovskite-based hybrid solar cells.

Organometal trihalide perovskite solar cells have in the few years since their first introduction (in 2009) demonstrated very high power conversion efficiencies, up to 21% with potential for further increase. It is announced to become a game changer in the field of thin film photovoltaics, but this will critically depend on avoiding defect formation in the perovskite layer as well as at the interfaces with adjacent layers. The defects act as trapping centers for negative and positive charge carriers and as such impede the carriers to contribute to the photocurrent. The defects may result from the material synthesis and device fabrication methods, but they can also appear due to degradation, thereby reducing the useful lifetime of the solar cells. The main goal of my project is the identification and characterization of the defects that set a limitation to the solar cell performance. To learn about the geometric and electronic structure of these defects I will apply multi-frequency electron paramagnetic resonance (EPR) techniques which are able to reveal the nature of the defects and of their surroundings. Knowledge of the electronic structure and creation processes of the defects will allow to design better perovskite materials for these solar cells and to optimize the device fabrication process.

Keywords:SPECTROSCOPY

Disciplines:Condensed matter physics and nanophysics

Project type:Collaboration project