|
Identifier |
000460778 |
Title |
Electrochemically active supramolecular entities in layered hybrid halide perovskites |
Alternative Title |
Ηλεκτροχημικά ενεργές & υπερμοριακές προσθήκες σε φυλλόμορφους υβριδικούς αλογονούχους περοβσκίτες |
Author
|
Μακροπούλου, Ελένη-Κων/να
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Thesis advisor
|
Στούμπος, Κωνσταντίνος
|
Reviewer
|
Αρματάς, Γεράσιμος
Σαββίδης, Πάυλος
|
Abstract |
Halide perovskites are exceptional and unconventional semiconductors, known for their
high optical absorption coefficients, extended charge carrier diffusion lengths, intense
photoluminescence, and slow rates of non-radiative charge recombination [1]. Layered
hybrid halide perovskites (AI2BIIX4 or AIIMIIX4, where A represents monovalent or
bivalent cations, M represents bivalent p- block metals, and X represents halide anions),
feature anionic sheets comprising corner- sharing metal-halide octahedra, selectively
partitioned by organic cations, creating crystallographically ordered nanoscale sheets.
This unique structure yields natural multiple quantum wells with stable excitonic
features, exhibiting intense photoluminescence characteristics, even at room temperature.
Intriguingly, a subset of these halide perovskites exhibits broadband optical emission,
generating white light via the self-trapped exciton mechanism [2]. Understanding this
fascinating trap-activated behavior necessitates careful material design, including the use
of various organic spacersthat can potentially induce or suppress this effect.
In this study, we have designed and synthesized a series of layered perovskites with
electrochemically-active spacers, where the electrochemical state of the spacer influences
the materials optical properties. The introduction of functional groups in the spacer cation
adds to the structural complexity by engaging in weak supramolecular interactions, acting
as perturbation probes to investigate the optical response concerning the electrochemical
state of the spacer cation. Specifically, we have synthesized two sister A2PbBr4
compounds (A+ = 2,3 dihydroxy-phenylethylammonium ((HO)2-PEA) and 2-(3-
aminoethyl)benzoic acid (HO2C-PEA)) as the redox-active and redox-inert pair of
compounds, exhibiting a similar supramolecular interaction environment within the
perovskite host. As evidenced by single-crystal X-ray diffraction experiments, the redox-
active compound readily crystallizes in its partially oxidized semiquinone form during
ambient environment synthesis, exhibiting similar photoluminescence characteristics to
the redox-inert compound. These observations suggest formation and rapid quenching of
the chemically reactive radical during the reaction. In order to probe this behavior, the
reaction system was treated with a variety of chemical redox reagents targeting to obtain
the compound in its fully reduced (catechol) and fully oxidized (quinone) form.
Simultaneous investigations into the electrocatalytic reaction mechanism using cyclic
voltammetry have indicated the presence of both the fully reduced form ((HO)2-
PEA)2PbBr4 and the fully oxidized ((O=C)2-PEA)2PbBr4 in solution, prompting further
optical and structural characterization of these metastable halide perovskite species.
|
Language |
English |
Subject |
Broadband optical emission |
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Crystallography |
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Cyclic voltammetrytructural characterization |
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Excitonic features |
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Optical properties |
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Photoluminescence |
|
Quantum wells |
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Self-trapped excitons |
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Semiconductor materials |
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Αυτο-παγιδευμένα εξιτόνια |
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Εκπομπή ευρέου φάσματος |
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Ηλεκτροχημικά-ενεργά κατιόντα |
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Ημιαγωγικά υλικά |
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Κρυσταλλογραφία |
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Κυκλική βολταμετρία |
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Οπτικές ιδιότητες |
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Οπτικός και δομικός χαρακτηρισμός |
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Υπερμοριακές αλληλεπιδράσεις |
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Φωτοφωταύγεια |
Issue date |
2023-11-29 |
Collection
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School/Department--School of Sciences and Engineering--Department of Materials Science and Technology--Post-graduate theses
|
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Type of Work--Post-graduate theses
|
Permanent Link |
https://elocus.lib.uoc.gr//dlib/9/a/b/metadata-dlib-1701422507-544934-25519.tkl
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Views |
1298 |