New insights into the nanostructure of innovative thin film solar cells gained by positron annihilation spectroscopy

[摘要] Recent studies showed that positron annihilation methods can provide key insights into the nanostructure and electronic structure of thin film solar cells. In this study, positron annihilation lifetime spectroscopy (PALS) is applied to investigate CdSe quantum dot (QD) light absorbing layers, providing evidence of positron trapping at the surfaces of the QDs. This enables one to monitor their surface composition and electronic structure. Further, 2D-Angular Correlation of Annihilation Radiation (2D-ACAR) is used to investigate the nanostructure of divacancies in photovoltaic-high-quality a-Si:H films. The collected momentum distributions were converted by Fourier transformation to the direct space representation of the electron-positron autocorrelation function. The evolution of the size of the divacancies as a function of hydrogen dilution during deposition of a-Si:H thin films was examined. Finally, we present a first positron Doppler Broadening of Annihilation Radiation (DBAR) study of the emerging class of highly efficient thin film solar cells based on perovskites.

[发布机构] Department of Radiation Science and Technology, Delft University of Technology, Delft; NL-2629 JB, Netherlands^1;Institut für Angewandte Physik und Messtechnik, Universität der Bundeswehr München, Neubiberg; D-85579, Germany^2;Physik-Department and Heinz Maier-Leibnitz Zentrum (MLZ), Technische Universität München, Garching; D-85748, Germany^3;Department of Chemistry, University of Maine, Orono; ME; 04469, United States^4;Department of Physics and Astronomy, Laboratory for Surface Science and Technology, University of Maine, Orono; ME; 04469, United States^5;Department of Physics, University of Antwerp, Antwerp; B-2020, Belgium^6;Department of Physics, Northeastern University, Boston; MA; 02115, United States^7;Photovoltaic Materials and Devices, Faculty of Electrical Engineering, Mathematics and Computer Science, Delft University of Technology, NL-2628 CD, Netherlands^8;Department of Materials and Interfaces, Weizmann Institute of Science, Rehovot; 76100, Israel^9

[关键词] Angular correlation of annihilation radiations;Autocorrelation functions;CdSe quantum dots;Doppler broadening of annihilation radiations;Fourier transformations;Momentum distributions;Positron annihilation lifetime spectroscopy;Positron trapping