Optoelectronic Properties of Cs2AgBiBr6 Thin Films: The Influence of the Precursor Stoichiometry
Maximilian Sirtl a, Melina Armer b, Lennart Reb c, Rik Hooijer a, Patrick Dörflinger b, Manuel Scheel c, Pandit Pallavi d, Roth Stefan d, Peter Müller-Buschbaum c, Vladimir Dyakonov b, Thomas Bein a
a University of Munich (LMU), Department of Chemistry and Center for Nanoscience (CeNS), 81377 Múnich, Alemania, Múnich, Germany
b Experimental Physics VI, Julius Maximilian University of Würzburg, 97074 Würzburg, Germany
c Technische Universität München, Lehrstuhl für Funktionelle Materialien, Physik Department, Germany, James-Franck-Straße, 1, Garching bei München, Germany
d DESY - Deutsches Elektronen-Synchrotron, Hamburg, Notkestraße, 85, Hamburg, Germany
nanoGe Perovskite Conferences
Proceedings of International Conference on Perovskite Thin Film Photovoltaics and Perovskite Photonics and Optoelectronics (NIPHO20)
Sevilla, Spain, 2020 February 23rd - 25th
Organizer: Hernán Míguez
Poster, Maximilian Sirtl, 028
Publication date: 25th November 2019

Cs2AgBiBr6 is a promising candidate in the search for lead-free alternatives for perovskites to be applied in solar cells. Yet, thin films solar cells comprising this material weren’t able to perform better than 2.5 % power-conversion efficiency so far, which can amongst others be related to exciton formation, as well as the large and indirect bandgap and a high trap density.[1][2][3][4]

In order to address these problems, we show in this work the influence of the precursor stoichiometry on the optoelectronic properties of this material in thin films. We show that by working with an excess of AgBr combined with a deficiency of BiBr3, the films show a significant increase in orientation while remaining almost phase pure.

Moreover, time resolved photoluminescence measurements show an improved charge carrier lifetime, as well as a higher intensity for steady state measurements while time-resolved microwave conductivity (TRMC) measurements reveal an increase in the conductivity. These findings altogether lead to an increase in the power-conversion efficienciy (PCE) of the resulting solar cells, caused by an increase in FF and JSC.

All authors thank the DFG for the funding of the e-conversion and NIM clusters

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