Upconversion photoluminescence of perovskite nanoparticles encapsulated in porous sub-micron spheres supporting Mie resonances.

Abstract Currently, halide perovskites are very perspective materials not only for photovoltaics but also for nanophotonic and especially nonlinear optics. These materials have already demonstrated high two-, three- and many- photon absorption coefficients, strong Kerr-nonlinearity, and high-efficient second harmonic generation. Easy and cheap fabrication gives halide perovskites a wide area for scientific research and engineering applications. However, to achieve the stability of perovskites is still a challenging task, which scientific community is working on. In this work, we study a new form of encapsulation of perovskite nanoparticles in sub-micron porous dielectric nanospheres. Due to small pores in such spheres, perovskites are not only protected from external factors, but also are confined in size, which brings several features in the photoluminescence emission. We also show resonant properties of spherical sub-micron particles, which can be used for enhancing upconversion photoluminescence intensity.

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Exploring the Structural Competition between the Black and the Yellow Phase of CsPbI3

Nanomaterials ◽

10.3390/nano11051282 ◽

2021 ◽

Vol 11 (5) ◽

pp. 1282

Author(s):

Ioannis Deretzis ◽

Corrado Bongiorno ◽

Giovanni Mannino ◽

Emanuele Smecca ◽

Salvatore Sanzaro ◽

...

Keyword(s):

Perovskite Phase ◽

Low Cost ◽

Δ Phase ◽

Nanocrystalline Structures ◽

Halide Perovskites ◽

The Stability ◽

Structural Competition ◽

Lead Halide ◽

Main Candidate ◽

Spontaneous Phase

The realization of stable inorganic perovskites is crucial to enable low-cost solution-processed photovoltaics. However, the main candidate material, CsPbI3, suffers from a spontaneous phase transition at room temperature towards a photo-inactive orthorhombic δ-phase (yellow phase). Here we used theoretical and experimental methods to study the structural and electronic features that determine the stability of the CsPbI3 perovskite. We argued that the two physical characteristics that favor the black perovskite phase at low temperatures are the strong spatial confinement in nanocrystalline structures and the level of electron doping in the material. Within this context, we discussed practical procedures for the realization of long-lasting inorganic lead halide perovskites.

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2D organic-inorganic hybrid perovskite materials for nonlinear optics

Nanophotonics ◽

10.1515/nanoph-2020-0038 ◽

2020 ◽

Vol 9 (7) ◽

pp. 1787-1810 ◽

Cited By ~ 3

Author(s):

Xiao Han ◽

Yongshen Zheng ◽

Siqian Chai ◽

Songhua Chen ◽

Jialiang Xu

Keyword(s):

Nonlinear Optical ◽

Second Harmonic ◽

Low Cost ◽

Laser Pulses ◽

Structural Features ◽

Photon Absorption ◽

Saturable Absorption ◽

Research Attention ◽

Inorganic Hybrid ◽

Quantum Well Structures

AbstractTwo-dimensional (2D) organic-inorganic hybrid perovskites feature characteristics of inherent quantum-well structures and intriguing optoelectronic properties, and have therefore attracted enormous research attention for their optical applications in light emitting, sensing, modulation, and telecommunication devices. The low-cost and solution-processed fabrications as well as alternative organic spacer cations endue 2D hybrid perovskites with higher tunability in optical and photonic applications. In particular, they demonstrate distinguished nonlinear optical characters such as second-harmonic generation (SHG), two-photon absorption (2PA), and saturable absorption (SA) under the excitation of laser pulses. Here, we discuss the construction of the various sorts of 2D hybrid perovskites with different structural features. We have also highlighted some representative properties and applications of these 2D hybrid perovskites in both linear and nonlinear optical regimes.

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On the stability of crystal lattices IX. Covariant theory of lattice deformations and the stability of some hexagonal lattices

Mathematical Proceedings of the Cambridge Philosophical Society ◽

10.1017/s0305004100022246 ◽

1942 ◽

Vol 38 (1) ◽

pp. 82-99 ◽

Cited By ~ 25

Author(s):

M. Born

Keyword(s):

Elastic Constants ◽

Hexagonal Lattice ◽

Covariant Theory ◽

Tensor Calculus ◽

Crystal Lattices ◽

New Form ◽

The Stability ◽

Central Forces

The theory of lattice deformations is presented in a new form, using the tensor calculus. The case of central forces is worked out in detail, and the results are applied to some simple hexagonal lattices. It is shown that the Bravais hexagonal lattice is unstable but the close-packed hexagonal lattice stable. The elastic constants of this lattice are calculated.

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OPTICAL NONLINEARITY VIA PHONONS AS AN INTERMEDIARY

Journal of Nonlinear Optical Physics & Materials ◽

10.1142/s0218863501000449 ◽

2001 ◽

Vol 10 (01) ◽

pp. 65-77 ◽

Cited By ~ 3

Author(s):

OU FA ◽

HE MINGGAO ◽

WU FUGEN

Keyword(s):

Second Harmonic ◽

Optical Nonlinearity ◽

Photon Absorption ◽

Saturation Phenomenon ◽

Sum Frequency ◽

Two Photon Absorption ◽

Two Photon ◽

Threshold Phenomenon ◽

Anti Stokes ◽

The Given

A new model to describe the origin of optical nonlinearity is presented. In this model, the interaction between light and medium is reduced to the coupling of photons with phonons, which occurs in the crystal lattice vibrating anharmonically. Then the optical nonlinearity originates from the nonlinear photon–phonon coupling or the interaction among phonons themselves. In this paper, more attention is drawn to the latter. By the given model, (1) degenerate and (2) nondegenerate parametric oscillations, (3) Stokes and (4) anti-Stokes Raman scattering, (5) sum-frequency and (6) second harmonic generation and (7) two-photon absorption are dealt with systematically and quantum-mechanically. The results of theoretical analysis show that the effects (1)–(4) are associated with threshold phenomenon, whereas the effects (5)–(7) with the saturation phenomenon.

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Effect of static local distortions vs. dynamic motions on the stability and band gaps of cubic oxide and halide perovskites

Materials Today ◽

10.1016/j.mattod.2021.05.021 ◽

2021 ◽

Author(s):

Xin-Gang Zhao ◽

Zhi Wang ◽

Oleksandr I. Malyi ◽

Alex Zunger

Keyword(s):

Band Gaps ◽

Halide Perovskites ◽

The Stability ◽

Local Distortions

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Interactions of picosecond laser pulses with organic molecules I. Two-photon fluorescence quenching and singlet states excitation in Rhodamine dyes

Proceedings of the Royal Society of London Series A - Mathematical and Physical Sciences ◽

10.1098/rspa.1972.0071 ◽

1972 ◽

Vol 328 (1572) ◽

pp. 97-121 ◽

Cited By ~ 68

Keyword(s):

Rhodamine 6G ◽

Second Harmonic ◽

Random Phase ◽

Stimulated Emission ◽

Photon Absorption ◽

Picosecond Pulses ◽

Two Photon ◽

Singlet States ◽

Two Photon Fluorescence ◽

Photon Fluorescence

Intensity dependent quenching and reversal of the two-photon fluorescence patterns in Rhodamine 6G and DPA, of picosecond pulses from a mode-locked ruby laser have been investigated by measurements of the two-photon fluorescence efficiencies of these dyes. While for Rhodamine 6G there was a marked departure from the square law dependence at high laser intensities, the experimental curve for DPA showed no evidence of quenching. When excited by a mode-locked neodymium: glass laser Rhodamine 6G fluorescence was not quenched at fluxes as high as 5 x 10 30 photons cm -2 s -1 but in Rhodamine B quenching appeared at a laser flux of 3 x 10 27 photons cm -2 s -1 . These quenching results and measurements of the absorption of pulses by Rhodamine 6G, previously excited by second harmonic pulses, are explained by the effects of single photon absorption and stimulated emission from the S 1 and S 2 excited singlet states. A square pulse approximation has been employed to solve the general rate equations and the fitting of the calculated curves to the experimental results gave values for the stimulated emission and absorption cross-sections of the S 1 and S 2 states of Rhodamine 6G and for the relaxation time (~ 2 ps) between the vibrational manifolds of these excited states. Taking into account random phase and amplitude fluctuations of the picosecond pulses, time and space averaged two-photon fluorescence profiles, using these values of the dye parameters, showed quenching and reversal of the patterns for the laser pulse intensities at which these effects were experimentally observed. The possibilities of frequency tunable pulses, of transform-limited durations, from mode-locked dye lasers employed with an electro-optical streak camera of time-resolution equal to that of the pulse durations (~ 2 ps) for time-resolved excited state molecular spectroscopy are briefly considered.

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Tailoring capping-layer composition for improved stability of mixed-halide perovskites

Journal of Materials Chemistry A ◽

10.1039/d1ta07870d ◽

2022 ◽

Author(s):

Noor Titan Putri Hartono ◽

Marie-Hélène Tremblay ◽

Sarah Wieghold ◽

Benjia Dou ◽

Janak Thapa ◽

...

Keyword(s):

Solar Cells ◽

Perovskite Solar Cells ◽

Capping Layer ◽

Improved Stability ◽

Halide Perovskites ◽

The Stability ◽

Low Dimensional ◽

Layer Composition

Incorporating a low dimensional (LD) perovskite capping layer on top of perovskite absorber, improves the stability of perovskite solar cells (PSCs). However, in the case of mixed-halide perovskites, which can...

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Poly(catecholamine) Coating and Biofunctionalization of CsPbBr3 Microcrystals

10.26434/chemrxiv.14049710.v2 ◽

2021 ◽

Author(s):

Sangyeon Cho ◽

Seok-Hyun Yun

Keyword(s):

Lipid Bilayers ◽

Environmental Stability ◽

Live Cells ◽

Functional Coatings ◽

Common Strategy ◽

Novel Method ◽

Halide Perovskites ◽

The Stability ◽

New Applications

Lead halide perovskites (LHP) microcrystals are promising materials for various optoelectronic applications. Surface coating on particles is a common strategy to improve their functionality and environmental stability, but LHP is not amenable to most coating chemistries because of its intrinsic weakness against polar solvents. Here, we describe a novel method of synthesizing LHP microcrystals in a super-saturated polar solvent using sonochemistry and applying various functional coatings on individual microcrystals in situ. We synthesize cesium lead bromine perovskite (CsPbBr3) microparticles capped with organic poly-norepinephrine (pNE) layers. The catechol group of pNE coordinates to bromine-deficient lead atoms, forming a defect-passivating and diffusion-blocking shell. The pNE layer enhances the stability of CsPbBr3 in water by 2,000-folds, enabling bright luminescence and lasing from single microcrystals in water. Furthermore, the pNE shell permits biofunctionalization with proteins, small molecules, and lipid bilayers. Luminescence from CsPbBr3 microcrystals is sustained in water over 1 hour and observed in live cells. The functionalization method may enable new applications of LHP particles in water-rich environments.

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Enhanced Luminescence and Mechanistic Studies on Mn-doped Double Layered Perovskite Phosphors: Cs4Mn1−xCdxBi2Cl12

10.26434/chemrxiv.12735584 ◽

2020 ◽

Author(s):

Brenda Vargas ◽

Diana T. Reyes-Castillo ◽

Eduardo Coutino-Gonzalez ◽

Citlali Sánchez-Aké ◽

Carlos Ramos ◽

...

Keyword(s):

Magnetic Coupling ◽

Layered Perovskite ◽

Great Promise ◽

New Family ◽

Halide Perovskites ◽

Optoelectronic Applications ◽

The Stability ◽

Low Dimensional ◽

Stability Issues ◽

Mn Doped

Halide perovskites offer great promise for optoelectronic applications, but stability issues continue to hinder its implementation and long-term stability. The stability of all-inorganic halide perovskites and the inherent quantum confinement of low dimensional perovskites can be harnessed to synthesize materials with high PL efficiency. An example of such materials is the recently reported new family of layered double perovskites, Cs4Mn1−xCdxBi2Cl12. Herein, we report a new synthetic procedure that enhances the maximum PLQY of this family materials to up 79.5%, a 20% enhancement from previous reports and the highest reported for a Mn-doped halide perovskite. Importantly, stability tests demonstrate that these materials are very stable towards humidity, UV irradiation, and temperature. Finally, we investigated the photophysics, the effects of magnetic coupling and temperature in the PL efficiency and proposed a mechanism for the emission process. Our results highlight the potential of this family of materials and related layered all-inorganic perovskites for solid-state lighting and optoelectronic applications

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