Dynamics of self-trapped hole processes in AgCl

Slifkin, Lawrence

doi:10.1088/0953-8984/13/10/325

Cited by 2 publications

(3 citation statements)

References 35 publications

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“…The trapped holes readily combine with more delocalized electrons (Coulomb attraction) to form STEs. Such a STE formation mechanism is similar to that of many materials such as alkali halides and AgCl. − …”

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confidence: 60%

One-Center and Two-Center Self-Trapped Excitons in Zero-Dimensional Hybrid Copper Halides: Tricolor Luminescence with High Quantum Yields

Liu

Liang

et al. 2022

J. Phys. Chem. Lett.

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The organic–inorganic hybrid copper halides exhibit intriguing and complex photophysical properties, and the underlying mechanisms are far from clear. Here, we study the photodynamics of six novel types of low-dimensional hybrid copper halides, which have a maximum quantum yield of 98.6%. They exhibit two origins of photon emission with distinct temperature dependence and quantum transition rates. The experiments in junction with first-principles calculations indicate that they stem from two kinds of self-trapped excitons (STEs): one-center a-STE (localized on Cu+ monomer) and two-center m-STE (localized on Cu2 2+ dimer). There is phase transition between a-STE and m-STE when enough thermal energy is acquired for crossing the potential barrier between them. The degree of softness of the compositional organic cations of the copper halide plays a key role in determining the self-trapping type of the STEs.

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confidence: 60%

One-Center and Two-Center Self-Trapped Excitons in Zero-Dimensional Hybrid Copper Halides: Tricolor Luminescence with High Quantum Yields

Liu

Liang

et al. 2022

J. Phys. Chem. Lett.

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“…Concerning silver halides, EPR, ENDOR, and cyclotron resonance data proved the formation of a STH in AgCl, but not in AgBr. [17][18][19]21,23,[25][26][27][28][29][30][31]35 As a salient feature, the nature of the self-trapped species in the cubic AgCl crystal, formed after ultraviolet irradiation, is rather different from that found in alkali halides as the top of the valence band involves a strong admixture of 3p(Cl) and 4d(Ag) wave functions. 29 Indeed, the resemblance of EPR data of KCl:Ag 2+ or NaCl:Ag 2+36,37 to those reported 19,21,23,35 for the STH in AgCl (Table 1) proves that this species can be viewed, in a first approximation, as an elongated AgCl 6 4− complex with the hole located in a x 2 −y 2 -type orbital resulting from a Jahn−Teller distortion.…”

Section: Introductionmentioning

confidence: 99%

“…Our chosen model systems are diamagnetic binary lattices with simple rocksalt structure, AgCl and AgBr, that have been extensively studied due to their relevance in photographic film technology. − As explained below, these experimental studies reveal important questions on the basic properties of polarons, making them ideal to study the physics of these quasi-particles in detail.…”

Section: Introductionmentioning

confidence: 99%

Stability and Polaronic Motion of Self-Trapped Holes in Silver Halides: Insight through DFT+UCalculations

et al. 2016

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Polarons and their associated transport properties are a field of great current interest both in chemistry and physics. In order to further our understanding of these quasi-particles, we have carried out first-principles calculations of self-trapped holes (STH) in the model compounds AgCl and AgBr, where extensive experimental information exists. Our calculations confirm that the STH solely stabilizes in AgCl but with a binding energy of only 165 meV, an order of magnitude smaller than that found for the Vk center in KCl. Key contributions to this stabilization energy come from the local relaxation along breathing (a1g) and Jahn-Teller (eg) modes in the AgCl6 4-unit. In order to study the transfer of the STH among silver sites we (i) use first-principles calculations to obtain the hopping barrier of the STH to first and second neighbors, involving eight distinct paths, using firstprinciples and (ii) construct a simple model, based on Slater-Koster parameters, that highlights the similarity of polaron transfer with magnetic superexchange. This allows one understanding why the movement of STH to second neighbors is highly enhanced with respect to closer ones. In agreement with experimental data and the model, the present calculations prove the existence of a dominant mechanism of polaronic motion that corresponds to the displacement of the STH to the next nearest sites in the <100> direction and a small barrier of 37 meV. This mechanism is dominated by the covalency inside a AgX6 4-complex (X:Cl;Br) thus explaining why the STH is not stabilized in AgBr following the increase of covalency due to the ClBr substitution. The present calculations confirm that ~10% of the charge associated with the STH in AgCl is lying outside the AgCl6 4-complex. This fact is behind the differences between optical and magnetic properties of the STH in AgCl and those observed in KCl:Ag 2+ .2

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Dynamics of self-trapped hole processes in AgCl

Cited by 2 publications

References 35 publications

One-Center and Two-Center Self-Trapped Excitons in Zero-Dimensional Hybrid Copper Halides: Tricolor Luminescence with High Quantum Yields

One-Center and Two-Center Self-Trapped Excitons in Zero-Dimensional Hybrid Copper Halides: Tricolor Luminescence with High Quantum Yields

Stability and Polaronic Motion of Self-Trapped Holes in Silver Halides: Insight through DFT+UCalculations

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