Journal Article

PUBDB-2016-04897

http://join2-wiki.gsi.de/foswiki/pub/Main/Artwork/join2_logo100x88.png Exciton Binding Energy and the Nature of Emissive States in Organometal Halide Perovskites

Zheng, K. ; Zhu, Q. ; Abdellah, M. ; Messing, M. E. ; Zhang, W. ; Generalov, A. ; Niu, Y. ; Ribaud, L. ; Canton, S. (Corresponding author)Extern*DESY* ; Pullerits, T. (Corresponding author)

2015
ACS Washington, DC

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Please use a persistent id in citations: doi:10.1021/acs.jpclett.5b01252

Abstract: Characteristics of nanoscale materials are often different from the corresponding bulk properties providing new, sometimes unexpected, opportunities for applications. Here we investigate the properties of 8 nm colloidal nanoparticles of MAPbBr$_3$ perovskites and contrast them to the ones of large microcrystallites representing a bulk. X-ray spectroscopies provide an exciton binding energy of 0.32 ± 0.10 eV in the nanoparticles. This is 5 times higher than the value of bulk crystals (0.084 ± 0.010 eV), and readily explains the high fluorescence quantum yield in nanoparticles. In the bulk, at high excitation concentrations, the fluorescence intensity has quadratic behavior following the Saha–Langmuir model due to the nongeminate recombination of charges forming the emissive exciton states. In the nanoparticles, a linear dependence is observed since the excitation concentration per particle is significantly less than one. Even the bulk shows linear emission intensity dependence at lower excitation concentrations. In this case, the average excitation spacing becomes larger than the carrier diffusion length suppressing the nongeminate recombination. From these considerations we obtain the charge carrier diffusion length in MAPbBr$_3$ of 100 nm.

Note: © American Chemical Society; Post referee fulltext in progress; Embargo 12 months from publication

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Contributing Institute(s):

1. Strukturdynamik Chemischer Systeme (FS-SCS)

Research Program(s):

1. 6213 - Materials and Processes for Energy and Transport Technologies (POF3-621) (POF3-621)

Experiment(s):

1. Measurement at external facility

Appears in the scientific report 2015

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Database coverage:
; Current Contents - Physical, Chemical and Earth Sciences ; IF >= 5 ; JCR ; NCBI Molecular Biology Database ; SCOPUS ; Science Citation Index ; Science Citation Index Expanded ; Thomson Reuters Master Journal List ; Web of Science Core Collection

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