Journal Article

PUBDB-2021-00957

http://join2-wiki.gsi.de/foswiki/pub/Main/Artwork/join2_logo100x88.png Optoelectronic Properties of $Cs_{2}AgBiBr_{6}$ Thin Films: The Influence of Precursor Stoichiometry

Sirtl, M. T. ; Armer, M. ; Reb, L. K.Extern* ; Hooijer, R. ; Dörflinger, P. ; Scheel, M. A.Extern* ; Tvingstedt, K. ; Rieder, P. ; Glück, N. ; Pandit, P.Extern*DESY* ; Roth, S. V.DESY* ; Müller-Buschbaum, P.Extern* ; Dyakonov, V.Extern* ; Bein, T. (Corresponding author)

2020
ACS Publications Washington, DC

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Please use a persistent id in citations: doi:10.1021/acsaem.0c01308

Abstract: Lead-free double perovskites have recently attracted growing attention as possible alternatives to lead-based halide perovskites in photovoltaics and other optoelectronic applications. The most prominent compound Cs$_2$AgBiBr$_6$, however, presents issues such as a rather large and indirect band gap, high exciton binding energies, and poor charge carrier transport, especially in thin films. In order to address some of these challenges, we systematically modified the stoichiometry of the precursors used for the synthesis of thin films toward a BiBr$_3$-deficient system. In combination with a stoichiometric excess of AgBr, we obtained highly oriented double perovskite thin films. These modifications directly boost the lifetime of the charge carriers up to 500 ns as observed by time-resolved photoluminescence spectroscopy. Moreover, time-resolved microwave conductivity studies revealed an increase of the charge carrier mobility from 3.5 to around ∼5 cm$^2$/(V s). Solar cells comprising the modified films as planar active layers reached power conversion efficiency (PCE) values up to 1.11%, exceeding the stoichiometric reference film (∼0.97%), both on average and with champion cells. The results in this work underline the importance of controlling the nanomorphology of the bulk film. We anticipate that control of precursor stoichiometry will also offer a promising approach for enhancing the efficiency of other perovskite photovoltaic absorber materials and thin films.

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Contributing Institute(s):

1. DOOR-User (DOOR ; HAS-User)
2. Experimentebetreuung PETRA III (FS-PET-D)

Research Program(s):

1. 6214 - Nanoscience and Materials for Information Technology (POF3-621) (POF3-621)
2. 6G3 - PETRA III (POF3-622) (POF3-622)

Experiment(s):

1. PETRA Beamline P03 (PETRA III)

Appears in the scientific report 2020

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Database coverage:
; Clarivate Analytics Master Journal List ; Current Contents - Engineering, Computing and Technology ; Current Contents - Physical, Chemical and Earth Sciences ; Essential Science Indicators ; SCOPUS ; Science Citation Index Expanded ; Web of Science Core Collection

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