Neutrons for Science and Industry

Point defects and their impact in next generation solar cells revealed by in-situ positron annihilation spectroscopy

by Dr Stephan Eijt (Delft University of Technology)

PH HS 3 (Physics Department)


Physics Department

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Positron Annihilation Spectroscopy (PAS) is a very sensitive method to reveal the presence of vacancy-related point defects in thin film solar cells. Its depth-range and resolution matches various types of existing and emerging thin film solar cells. We apply Positron annihilation spectroscopy (PAS) to monitor environmental degradation of ZnO/CIGS and of perovskite solar cells. Furthermore, we examine the presence of point defects and near-surface oxidation of thermally annealed RF-sputtered BaSi2 thin films. We show that the positron is a very sensitive probe for the surfaces of semiconductor quantum dots in thin film QD photovoltaic systems. Ab-initio modelling in combination with Positron Annihilation Lifetime Spectroscopy (PALS) provided first-time proof of the presence of the positron surface state underlying the very high sensitivity of positrons to probe surfaces of CdSe quantum dots.

Organized by

Dr.Alexandros Koutsioumpas
Dr. Christian Franz