10-11 December 2019
Europe/Berlin timezone

Evolution of vacancies in thin film solar cells and in photochromic yttrium oxyhydride revealed by in-situ positron annihilation spectroscopy

10 Dec 2019, 13:40
Marriott Conference room - Munich (Marriott)

Marriott Conference room - Munich


Berliner Str. 93 80805 München Germany
Show room on map
Invited talk Positrons Positrons


Stephan Eijt (Delft University of Technology)


We apply Positron Annihilation Spectroscopy (PAS) to monitor the environmental degradation of ZnO/CIGS and perovskite thin film solar cells. Furthermore, yttrium oxy-hydride thin films are studied in view of their special photochromic properties, with the aim to elucidate the nature of vacancies in YOxHy and their evolution under in-situ UV illumination.

Our PALS study of as-deposited perovskite films using the PLEPS spectrometer reveals the presence of cation vacancies. Positron Doppler Broadening (DB-PAS) indicates that the degradation of MAPbI3 films involves the ingress of water molecules into the cation vacancies. In parallel, chemical transformations and a reduction in film thickness are observed, that proceed as a function of air exposure time.

PALS studies of ZnO:Al transparent electrode films on CIGS solar cells reveals a pronounced growth of vacancy clusters at the grain boundaries of the ZnO upon accelerated degradation at 85 oC/85% relative humidity. The growth of the vacancy clusters correlates with the observed degradation of the solar cell efficiency, pointing to a key role in the mechanism of degradation.

Finally, PALS reveals the presence of vacancies and micropores in photochromic YOxHy films. In-situ illumination DB-PAS studies show an increase in the S-parameter and a strong reduction in W, indicating that the generation of additional vacancies and/or a change in the charge state of vacancies accompanies the formation of the photochromic state.

Primary author

Stephan Eijt (Delft University of Technology)


Mrs Dibya Koushik (Eindhoven University of Technology) Mrs Frideriki Naziris (Delft University of Technology) Dr Wenqin Shi (Delft University of Technology) Dr Mirjam Theelen (Solliance Solar Research) Mr Tom de Krom (Delft University of Technology) Mrs Diana Chaykina (Delft University of Technology) Dr Henk Schut (Delft University of Technology) Dr Werner Egger (Universität der Bundeswehr München) Dr Marcel Dickmann (Universität der Bundeswehr München) Prof. Christoph Hugenschmidt (Heinz Maier-Leibnitz Zentrum (MLZ), Technische Universität München) Dr Adriana Creatore (Eindhoven University of Technology) Dr Olindo Isabella (Delft University of Technology) Prof. Miro Zeman (Delft University of Technology) Prof. Bernard Dam (Delft University of Technology)

Presentation Materials

There are no materials yet.