Unraveling luminescence mechanisms in zero-dimensional halide perovskites

Dan Han, Hongliang Shi, Wenmei Ming, Chenkun Zhou, Biwu Ma, Bayrammurad Saparov, Ying Zhong Ma, Shiyou Chen, Mao Hua Du

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    182 Scopus citations

    Abstract

    Zero-dimensional (0D) halides perovskites, in which anionic metal-halide octahedra (MX6)4- are separated by organic or inorganic countercations, have recently shown promise as excellent luminescent materials. However, the origin of the photoluminescence (PL) and, in particular, the different photophysical properties in hybrid organic-inorganic and all inorganic halides are still poorly understood. In this work, first-principles calculations were performed to study the excitons and intrinsic defects in 0D hybrid organic-inorganic halides (C4N2H14X)4SnX6 (X = Br, I), which exhibit a high photoluminescence quantum efficiency (PLQE) at room temperature (RT), and also in the 0D inorganic halide Cs4PbBr6, which suffers from strong thermal quenching when T > 100 K. We show that the excitons in all three 0D halides are strongly bound and cannot be detrapped or dissociated at RT, which leads to immobile excitons in (C4N2H14X)4SnX6. However, the excitons in Cs4PbBr6 can still migrate by tunneling, enabled by the resonant transfer of excitation energy (Dexter energy transfer). The exciton migration in Cs4PbBr6 leads to a higher probability of trapping and nonradiative recombination at the intrinsic defects. We show that a large Stokes shift and the negligible electronic coupling between luminescent centers are important for suppressing exciton migration; thereby, enhancing the photoluminescence quantum efficiency. Our results also suggest that the frequently observed bright green emission in Cs4PbBr6 is not due to the exciton or defect-induced emission in Cs4PbBr6 but rather the result of exciton emission from CsPbBr3 inclusions trapped in Cs4PbBr6.

    Original languageEnglish
    Pages (from-to)6398-6405
    Number of pages8
    JournalJournal of Materials Chemistry C
    Volume6
    Issue number24
    DOIs
    StatePublished - 2018

    Funding

    † This manuscript has been authored by UT-Battelle, LLC under Contract No. DE-AC05-00OR22725 with the U.S. Department of Energy. The United States Government retains and the publisher, by accepting the article for publication, acknowledges that the United States Government retains a non-exclusive, paid-up, irrevocable, world-wide license to publish or reproduce the published form of this manuscript, or allow others to do so, for United States Government purposes. The Department of Energy will provide public access to these results of federally sponsored research in accordance with the DOE Public Access Plan (http://energy.gov/downloads/doe-public-access-plan). ‡ Electronic supplementary information (ESI) available. See DOI: 10.1039/c8tc01291a § Both authors contributed equally to this work. The work at ORNL were supported by the U.S. Department of Energy, Office of Science, Basic Energy Sciences, Materials Sciences and Engineering Division (W. Ming and M.-H. Du) and the Chemical Sciences, Geosciences, and Biosciences Division (Y.-Z. Ma). D. Han and S. Chen were supported by the State Scholarship Fund in China and CC of ECNU. H. Shi was supported by the National Natural Science Foundation of China (NSFC) under Grant No. 11604007 and the start-up funding at Beihang University. B. Ma was supported by the Florida State University Energy and Materials Initiative and the National Science Foundation (DMR-1709116).

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