Tunable exciton binding energy in 2D hybrid layered perovskites through donor–acceptor interactions within the organic layer

Passarelli, James; Mauck, Catherine M.; Winslow, Samuel W.; Perkinson, Collin F.; Bard, Jacob C.; Sai, Hiroaki; Williams, Kristopher; Narayanan, Ashwin; Fairfield, Daniel J.; Hendricks, Mark P.; Tisdale, William A.; Stupp, Samuel I.

doi:10.1038/s41557-020-0488-2

Cited by 159 publications

(154 citation statements)

References 72 publications

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“…Unlike in the case of (PEA) 2 PbI 4 , here we do not observe a clear continuum edge and accordingly we cannot reproduce the lineshape using the Elliott's formalism. We note that the empirically modified Elliott's formalism used by Neutzner et al 38,39 and Passarelli et al 40 to reproduce the absorption spectrum of (PEA) 2 PbI 4 is also insufficient for the lineshape shown in Fig. 1(a).…”

Section: Resultsmentioning

confidence: 81%

The Effect of Tin Substitution on the Excitonic Properties of Two Dimensional Metal Halide Perovskites

Folpini¹,

Palummo²,

Cortecchia³

et al. 2021

Preprint

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<div>With growing interest in the lead-free derivatives of the metal-halide perovskites (MHP), it is imperative to fully understand the contribution of the metal cation to their desirable excitonic characteristics. Here, we explore this question by performing an in-depth spectroscopic and theoretical analysis of phenethylammonium tin iodide ((PEA)<sub>2</sub>SnI<sub>4</sub>), a prototypical tin based MHP, and rigorously compare it with its lead counterpart. We elaborate on the origin of multiple excitonic resonances uniquely observed in the linear absorption spectrum of (PEA)<sub>2</sub>SnI<sub>4</sub> at energies about 200-300meV above the primary exciton. By performing calculations based on density functional theory and many- body perturbation theory, we suggest that the excitonic series at these higher energies are composed of electronic transitions from a lower lying valence band. Importantly, the valence band splitting is driven by the octahedral conformations that follow subtle variations in the organic-inorganic interactions within the crystal lattice. We experimentally show that the presence of the higher energy excitonic resonance results in a relatively slow nanosecond component in the formation dynamics of the primary exciton, in addition to the ultrafast phonon-driven hot carrier thermalization. While the presence of such slow relaxation channel for the excitons might be beneficial to many optoelectronic applications, our work suggests its possible control via systematic design of the organic cation. Moreover, our observations indicate that spin-orbit coupling does not play a primary role in the intricate yet crucial changes in the excitonic characteristics imparted by the tin substitution.</div>

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Section: Resultsmentioning

confidence: 81%

The Effect of Tin Substitution on the Excitonic Properties of Two Dimensional Metal Halide Perovskites

Folpini¹,

Palummo²,

Cortecchia³

et al. 2021

Preprint

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“…We experimentally confirm the effect of dielectric confinement by modifying NPL external environment and showing a noticeable shift in exciton binding energy, consistent with similar measurements in 2D TMDCs and perovskites. 28,42,44 Uncovering the exciton binding energies of NPLs and understanding how external dielectric screening modulates these resonances further establishes the distinct properties of nanoplatelets that distinguish them from their quantum dot counterparts.…”

Section: Discussionmentioning

confidence: 99%

“…layered perovskites-but has not been applied to NPLs. 16,[24][25][26][27][28] In Fig. 2a, we illustrate the electronic structure of II-VI NPLs and highlight the transitions that are well-described by the Elliott model.…”

Section: A Multiband Elliott Model Of Colloidal Npl Systemsmentioning

confidence: 99%

“…To confirm the extent to which external dielectric contrast modulates exciton binding energy, we change the solvent environment, similar to previous work in TMDCs and 2D perovskites. 28,42,43 We measure and using the above Elliott model fit of the absorption spectrum of 3 ML HgTe NPLs (Fig. 4a-1), initially suspended in hexanes ( ≈ 1.9 ).…”

Section: Dielectric Screeningmentioning

confidence: 99%

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Dielectric Screening Modulates Semicondcutor Nanoplatelet Excitons

Shin¹,

Hossain²,

Tenney³

et al. 2021

Preprint

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The influence of external dielectric environments is well understood for 2D semiconductor materials but is overlooked for colloidally-grown II-VI nanoplatelets (NPLs). In this work, we synthesize MX (M=Cd, Hg; X= Se, Te) NPLs of varying thicknesses, and apply a modified Elliott model to fit excitonic absorption features and report exciton binding energies for cadmium telluride and mercury chalcogenides for the first time. Our observations indicate that the exciton binding energy is modulated by the dielectric screening of semiconductor material by the external ligand environment. Furthermore, NPL binding energies show a dependence on the number of monolayers consistent with relative effect of internal vs. external dielectric. To describe this, we derive an analytical electrostatic model, reinforcing the hypothesis that the external environment increases the exciton binding energy relative to the bulk—due to the distortion of the Coulombic potential across the NPL surface. We further confirm this effect by decreasing and recovering the exciton binding energy of HgTe NPLs through washing in polarizable solvents. Our results illustrate that NPLs are colloidal analogues of Van der Waals 2D semiconductors and point to surface modification as an approach to control photophysics and device properties.

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“…Molecular engineering has been exploited to tune the behaviors of electronic forms of energy in electronic materials and thus the performance of related (opto)electronic devices. Recent work by Passarelli et al 29 shows that the exciton binding energy of two-dimensional hybrid perovskites can be tuned by a molecular doping approach, via incorporation of a tetrachloro-1,2-benzoquinone TCBQ molecule into the naphthalene-containing organic lattice of a layered perovskite (Figure 2a). The donor-acceptor interactions between the electron-donating naphthalene and the electron-accepting TCBQ dopant lead to increased electrostatic screening of the exciton.…”

Section: Molecular Engineering Of Electronic and Electrochemical Materialsmentioning

confidence: 99%

Rational design of charge-functional materials: Insights from molecular engineering and operando imaging

Mao

2021

MRS Bulletin

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Emerging charge-functional electronic and electrochemical materials exhibit increasingly complex structure. Critical fundamental processes (e.g., charge transport, electrocatalysis) must work cooperatively across multiple time-and length scales to realize desired properties. Performance optimization in these materials demands an ultimate multifaceted, multiscale understanding of structure versus charge-function relationships, in order to address longstanding challenges associated with, for example, climate change, clean water, and humanmachine interfacing. Across seemingly different applications (e.g., energy conversion, water desalination, biosensing), the overall system performance is governed by the same set of interrelated fundamental physiochemical processes, such as electronic transport, ionic transport, and interfacial electrocatalysis. In this article, we discuss how to approach rational design of charge-functional electronic and electrochemical materials by elucidating performance-governing fundamental processes, with a particular focus on insights obtained from molecular engineering and operando imaging of emerging material systems important for sustainability and health care.

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Tunable exciton binding energy in 2D hybrid layered perovskites through donor–acceptor interactions within the organic layer

Cited by 159 publications

References 72 publications

The Effect of Tin Substitution on the Excitonic Properties of Two Dimensional Metal Halide Perovskites

The Effect of Tin Substitution on the Excitonic Properties of Two Dimensional Metal Halide Perovskites

Dielectric Screening Modulates Semicondcutor Nanoplatelet Excitons

Rational design of charge-functional materials: Insights from molecular engineering and operando imaging

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