Single-molecule studies beyond optical imaging: Multi-parameter single-molecule spectroscopy

Vácha, Martin; Sharma, Dipti; Hirata, Shuzo

doi:10.1016/j.jphotochemrev.2017.11.003

Cited by 11 publications

(6 citation statements)

References 125 publications

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“…Fluorescence microscopy in combination with other techniques has served as a powerful tool to find nanoscale structure–function relationships in a variety of materials, including perovskite thin films, , and has provided insight into potential sources of nonradiative loss , and heterogeneity in perovskites. , Further studies using photoluminescence (PL) and electroluminescence (EL) imaging and spectroscopy have revealed the local photophysics of a variety of other perovskite materials, such as micro- and nanocrystals or quantum dots. − Effective utilization of these fluorescence techniques can give access to local energy transport, grain boundaries, and charge pathways to help rationally control these fundamental processes and improve the efficiency of solar cells, light-emitting diodes, or lasers. − …”

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confidence: 99%

“…These materials are largely limited by the grain boundaries 13,14 and by the presence of defects 8,9,15,22 that can trap photogenerated charge carriers 10,11,16 and lead to their nonradiative recombination 12,17−20 and structural heterogeneity. 15,16,21 Fluorescence microscopy in combination with other techniques has served as a powerful tool to find nanoscale structure−function relationships in a variety of materials, 23 including perovskite thin films, 24,25 and has provided insight into potential sources of nonradiative loss 20,21 and heterogeneity in perovskites. 14,15 Further studies using photoluminescence (PL) and electroluminescence (EL) imaging and spectroscopy have revealed the local photophysics of a variety of other perovskite materials, such as micro-and nanocrystals or quantum dots.…”

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confidence: 99%

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Nanoscale Structural Heterogeneity and Efficient Intergrain Charge Diffusion in a Series of Mixed MA/FA Halide Perovskite Films

2022

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Perovskite solar cells have made tremendous technological progress, but knowledge of the fundamental photophysical properties of perovskite materials is equally important for further advancement of the field. We use fluorescence microscopy to study the nanoscale properties of a series of mixed-cation perovskite MA 1−x FA x PbI 3 films, an important photovoltaic material. Measuring photoluminescence spectra on submicrometer scales reveals the compositional heterogeneity of the films. The heterogeneity is largest for the FA 50% fraction films which contain purely MA domains, purely FA domains, as well as domains composed of mixed MA/FA cations of varying ratios. The films also show photoluminescence intensity fluctuations (blinking), which reflects dynamic nonradiative quenching. The quenching is most suppressed for the FA 50% films which contain the truly mixed MA/FA domains. Further, the blinking is correlated between locations that are micrometers apart, indicating that the grain boundaries do not function as traps and are transparent toward efficient charge migration.

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confidence: 99%

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Nanoscale Structural Heterogeneity and Efficient Intergrain Charge Diffusion in a Series of Mixed MA/FA Halide Perovskite Films

2022

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“…Single-particle imaging and spectroscopy are excellent tools to probe the effects of local environment on PL properties of molecules or nanoparticles. 17−19 It has been successfully used to uncover the effects of externally applied electric field in organic semiconductors 18,20 as well as to study the mechanism of electroluminescence (EL) on the level of single molecules. 18,21,22 Single-particle spectroscopy has been also applied to perovskite materials, including CsPbBr 3 , to understand their photophysics, degradation mechanism, and photoblinking behavior.…”

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confidence: 99%

“…Single-particle imaging and spectroscopy are excellent tools to probe the effects of local environment on PL properties of molecules or nanoparticles. − It has been successfully used to uncover the effects of externally applied electric field in organic semiconductors , as well as to study the mechanism of electroluminescence (EL) on the level of single molecules. ,, Single-particle spectroscopy has been also applied to perovskite materials, including CsPbBr 3 , to understand their photophysics, degradation mechanism, and photoblinking behavior. ,− Temporal fluctuations in PL intensity or photoblinking have been observed not only for perovskite quantum dots (QDs) , but also their aggregates and microcrystals, , where at times spatially correlated blinking over the entire crystal is visible . The magnitude of the blinking phenomenon is also directly correlated with efficiency of LED devices.…”

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Stark Effect and Environment-Induced Modulation of Emission in Single Halide Perovskite Nanocrystals

et al. 2019

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Organic–inorganic halide perovskites have emerged as promising materials for next-generation solar cells. In nanostructured form also, these materials are excellent candidates for optoelectronic applications such as lasers and light-emitting diodes for displays and lighting. While great progress has been achieved so far in optimizing the intrinsic photophysical properties of perovskite nanocrystals (NCs), in working optoelectronic devices, external factors, such as the effects of conducting environment and the applied electric field on exciton generation and photon emission, have been largely unexplored. Here, we use NCs of the all-inorganic perovskite CsPbBr3 dispersed polyvinyl carbazole, a hole-conductor, and in poly(methyl methacrylate), an insulator, to examine the effects of applied electric field and conductivity of the matrix on the perovskite photophysics at the single-particle level. We found that the conducting environment causes a significant decrease of photoluminescence (PL) brightness of individual NCs due the appearance of intermediate-intensity emitting states with significantly shortened lifetime. Applied electric field has a similar effect and, in addition, causes a nonlinear spectral shift of the PL maxima, a combination of linear and quadratic Stark effects caused by environment-induced polarity and field-related polarizability. The environment and electric-field effects are explained by ionization of the NCs through hole transfer and emission of the resulting negatively charged excitons.

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“…[18] In fact, according to recent reports, it is controversial to demonstrate that fluorescence comes from a single emitter by antibunching phenomenon and to judge whether fluorescence comes from a single quantum dot or nanocrystal emission using antibunching. [19][20][21][22][23] For example, a strong photon antibunching can be observed from a single cluster of giant CdSe/CdS nanocrystals, this behavior is thought to be the result of Auger annihilation of photo-excited excitons from different nearby nanocrystals so that only one single exciton is eventually left to emit a photon, [22] even it can be observed the transform from single-photon emission to multiphoton emission from a single colloidal nanocrystal quantum dots (NQDs) as the distance between the NQDs and Ag Tip, caused by using a silver-coated AFM. [20] In addition, a single sub-10-nm upconverting nanoparticle exhibits bunching light in antibunching measurement.…”

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Single Non‐Blinking Graphene Quantum Dots Identified by Single‐Particle Catalysis

Cao

Cheetham

2023

Advanced Optical Materials

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Quantum dots (QDs) with non‐blinking applied in bio‐imaging is important for understanding cellular dynamics by monitoring single particles in living cells. Antibunching is once believed to be applied to identify a single QD, which shows a strong dependence on the atom or ion number. However, recent works indicate that the antibunching alone may not be sufficient to demonstrate that the fluorescence comes from a single QD. To some extent, it is neither necessary nor sufficient for a single QD, though it is absolutely right for a single atom because a single QD is composed of thousands of atoms, which in principle are favorable to the formation of multi‐excitonic states. Blinking behavior, almost unobservable in ensembles due to the averaging, is characteristic of the single QD which owns the quantum effect due to its discrete energy levels. Here, a method of transformation of a single graphene quantum dot from non‐blinking to blinking via catalytic reaction to identify a single QD is reported, which can also help with understanding the catalytic dynamics of a single QD, which is a complementary means of confirming a single QD. The reported technique paves the way to understanding a single QD and its catalytic and kinetic behaviors.

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Single-molecule studies beyond optical imaging: Multi-parameter single-molecule spectroscopy

Cited by 11 publications

References 125 publications

Nanoscale Structural Heterogeneity and Efficient Intergrain Charge Diffusion in a Series of Mixed MA/FA Halide Perovskite Films

Nanoscale Structural Heterogeneity and Efficient Intergrain Charge Diffusion in a Series of Mixed MA/FA Halide Perovskite Films

Stark Effect and Environment-Induced Modulation of Emission in Single Halide Perovskite Nanocrystals

Single Non‐Blinking Graphene Quantum Dots Identified by Single‐Particle Catalysis

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