In this work, we apply single-molecule fluorescence microscopy and spectroscopy to probe plasmon-enhanced fluorescence and Förster resonance energy transfer in a nanoscale assemblies. The structure ...where the interplay between these two processes was present consists of photoactive proteins conjugated with silver nanowires and deposited on a monolayer graphene. By comparing the results of continuous-wave and time-resolved fluorescence microscopy acquired for this structure with those obtained for the reference samples, where proteins were coupled with either a graphene monolayer or silver nanowires, we find clear indications of the interplay between plasmonic enhancement and the energy transfer to graphene. Namely, fluorescence intensities calculated for the structure, where proteins were coupled to graphene only, are less than for the structure playing the central role in this study, containing both silver nanowires and graphene. Conversely, decay times extracted for the latter are shorter compared to a protein-silver nanowire conjugate, pointing towards emergence of the energy transfer. Overall, the results show that monitoring the optical properties of single emitters in a precisely designed hybrid nanostructure provides an elegant way to probe even complex combination of interactions at the nanoscale.
In this contribution, we fabricate hybrid constructs based on a natural light-harvesting complex, peridinin–chlorophyll a–protein, coupled to dimer optical antennas self-assembled with the help of ...the DNA origami technique. This approach enables controlled positioning of individual complexes at the hotspot of the optical antennas based on large, colloidal gold and silver nanoparticles. Our approach allows us to selectively excite the different pigments present in the harvesting complex, reaching a fluorescence enhancement of 500-fold. This work expands the range of self-assembled functional hybrid constructs for harvesting sunlight and can be further developed for other pigment–proteins and proteins.
Halide perovskites are emerging as valid alternatives to conventional photovoltaic active materials owing to their low cost and high device performances. This material family also shows exceptional ...tunability of properties by varying chemical components, crystal structure, and dimensionality, providing a unique set of building blocks for new structures. Here, highly stable self‐assembled lead–tin perovskite heterostructures formed between low‐bandgap 3D and higher‐bandgap 2D components are demonstrated. A combination of surface‐sensitive X‐ray diffraction, spatially resolved photoluminescence, and electron microscopy measurements is used to reveal that microstructural heterojunctions form between high‐bandgap 2D surface crystallites and lower‐bandgap 3D domains. Furthermore, in situ X‐ray diffraction measurements are used during film formation to show that an ammonium thiocyanate additive delays formation of the 3D component and thus provides a tunable lever to substantially increase the fraction of 2D surface crystallites. These novel heterostructures will find use in bottom cells for stable tandem photovoltaics with a surface 2D layer passivating the 3D material, or in energy‐transfer devices requiring controlled energy flow from localized surface crystallites to the bulk.
Lead–tin‐based perovskites represent a promising route for achieving low‐gap perovskite solar absorbers and light‐emitters. Films composed of heterostructures of 2D and 3D lead–tin perovskite domains are fabricated with distinctively unique optoelectronic properties. These tunable structures enhance the understanding of the growth and optoelectronic properties of 2D/3D perovskite heterojunctions, and will see use in energy funneling and passivating structures.
Plasmonics with Metallic Nanowires Niedziółka-Jönsson, Joanna; Mackowski, Sebastian
Materials,
05/2019, Letnik:
12, Številka:
9
Journal Article
Recenzirano
Odprti dostop
The purpose of this review is to introduce and present the concept of metallic nanowires as building-blocks of plasmonically active structures. In addition to concise description of both the basic ...physical properties associated with the electron oscillations as well as energy propagation in metallic nanostructures, and methods of fabrication of metallic nanowires, we will demonstrate several key ideas that involve interactions between plasmon excitations and electronic states in surrounding molecules or other emitters. Particular emphasis will be placed on the effects that involve not only plasmonic enhancement or quenching of fluorescence, but also propagation of energy on lengths that exceed the wavelength of light.
The MAPb1–x Sn x I3 (x = 0–1) (MA = methylammonium) perovskite family comprises a range of ideal absorber band gaps for single- and multijunction perovskite solar cells. Here, we use spectroscopic ...measurements to reveal a range of hitherto unknown fundamental properties of this materials family. Temperature-dependent transmission results show that the temperature of the tetragonal to orthorhombic structural transition decreases with increasing tin content. Through low-temperature magnetospectroscopy, we show that the exciton binding energy is lower than 16 meV, revealing that the dominant photogenerated species at typical operational conditions of optoelectronic devices are free charges rather than excitons. The reduced mass increases approximately proportionally to the band gap, and the mass values (0.075–0.090m e) can be described with a two-band k·p perturbation model extended across the broad band gap range of 1.2–2.4 eV. Our findings can be generalized to predict values for the effective mass and binding energy for other members of this family of materials.
Grain size in polycrystalline halide perovskite films is known to have an impact on the optoelectronic properties of the films, but its influence on their soft structural properties and phase ...transitions is unclear. Here, temperature‐dependent X‐ray diffraction, absorption, and macro‐ and micro‐photoluminescence measurements are used to investigate the tetragonal to orthorhombic phase transition in thin methylammonium lead iodide films with grain sizes ranging from the micrometer scale down to the tens of nanometer scale. It is shown that the phase transition nominally at ≈150 K is increasingly suppressed with decreasing grain size and, in the smallest grains, the first evidence of a phase transition is only seen at temperatures as low as ≈80 K. With decreasing grain size, an increasing magnitude of the hysteresis is also seen in the structural and optoelectronic properties when cooling to, and then upon heating from, 100 K. This work reveals the remarkable sensitivity of the optoelectronic, physical, and phase properties to the local environment of the perovskite structure, which will have large ramifications for phase and defect engineering in operating devices.
Temperature‐dependent X‐ray diffraction, absorption and photoluminescence measurements on methylammonium lead iodide thin films with grain sizes ranging from the micrometer to the tens of nanometer scale reveal that the low‐temperature phase transition is increasingly suppressed with decreasing grain size. These results unveil the remarkable sensitivity of optoelectronic and structural properties to the local environment in perovskite thin films.
Perovskite nanoplatelets (NPls) hold promise for light-emitting applications, having achieved photoluminescence quantum efficiencies approaching unity in the blue wavelength range, where other ...metal-halide perovskites have typically been ineffective. However, the external quantum efficiencies (EQEs) of blue-emitting NPl light-emitting diodes (LEDs) have reached only 0.12%. In this work, we show that NPl LEDs are primarily limited by a poor electronic interface between the emitter and hole injector. We show that the NPls have remarkably deep ionization potentials (≥6.5 eV), leading to large barriers for hole injection, as well as substantial nonradiative decay at the NPl/hole-injector interface. We find that an effective way to reduce these nonradiative losses is by using poly(triarylamine) interlayers, which lead to an increase in the EQE of the blue (464 nm emission wavelength) and sky-blue (489 nm emission wavelength) LEDs to 0.3% and 0.55%, respectively. Our work also identifies the key challenges for further efficiency increases.
Novel symmetrical anthracene derivatives with bulky carbazolyl‐fluorene, diphenylamino‐fluorene, or carbazolyl‐carbazole units connected to the anthracene frame through an ethynyl bridge were ...synthesized in excellent yield by using Sonogashira cross‐coupling. The ethynyl bridge in the anthracene dyes increases π‐electron conjugation and the bulky substituents considerably attenuate intermolecular interactions. The dyes possess high thermal stability, tremendous solubility in common organic solvents, and especially high photoluminescence quantum yield (Φf) in solution in the range of 77–98 %. OLED devices were fabricated. The AFM images of thin films and blends prepared from all compounds show a uniform and flat surface, indicating excellent film‐forming properties. Devices incorporating the anthracene derivative with diphenylamino‐fluorene end‐capping groups exhibited the highest value of current density (J). All of the fabricated OLED devices emitted yellowish‐orange light under applied voltage.
Symmetrical anthracene derivatives with bulky units connected to the anthracene frame through an ethynyl bridge were synthesized and their electrochemical, photophysical, and electrical properties were characterized. The compounds were yellowish‐orange emitters with high thermal stability, had excellent solubility in most organic solvents, and very high photoluminescence quantum yield in solution.
Novel 1,8-naphthalimides core substituted at 3-C position via imine bond with carbazole, benzothiazole, methylindole, quinoline, benzoindole, phenylmorpholine and triphenylamine derivatives were ...designed, synthesized and investigated with regard to their thermal, electrochemical, and luminescence behavior. DSC measurements showed that the obtained crystalline compounds can be converted into amorphous materials with glass transition temperatures in the range of 28–54 °C, except for the molecule bearing benzoindole derivative. The prepared compounds were thermally stable with the onset of thermal decomposition in the range of 345–368 °C. Energy band gap electrochemically estimated was modulated from 2.13 to 2.52 eV. Effect of excitation wavelength on the photoluminescence relative intensity of those naphthalimides in solution was detected. Their photoluminescence maximum band was located in the range of 495–560 nm in solution with the quantum yield from 0.2 to 14.0%. In the film, they emitted light in the blue and green spectral region with quantum yields from 1.1 to 3.6%. The electroluminescence ability of core substituted 1,8-naphthalimides was tested in the single-layer diode geometry. They were utilized as an emitting layer for both non-doped and doped single-layer OLEDs fabricated by solution processing. Additionally, calculations using density functional theory were performed to obtain the optimized ground-state geometry and distribution of the HOMO and LUMO levels of the synthesized molecules.
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•The effect of the substituent attached via imine to the naphthalimide core was studied.•The crystalline AzNIs could be converted into amorphous materials except for one with benzoindole.•All molecules showed value of Eg below 3 eV required for organic electronics.•The presence of benzothiazole and quinoline units reduced the PL quantum yields of AzNIs in solution.•AzNIs with carbazole, benzoindole and triphenylamine seem to be the most promising for further investigations.
The effects of combining naturally evolved photosynthetic pigment-protein complexes with inorganic functional materials, especially plasmonically active metallic nanostructures, have been a widely ...studied topic in the last few decades. Besides other applications, it seems to be reasonable using such hybrid systems for designing future biomimetic solar cells. In this paper, we describe selected results that point out to various aspects of the interactions between photosynthetic complexes and plasmonic excitations in Silver Island Films (SIFs). In addition to simple light-harvesting complexes, like peridinin-chlorophyll-protein (PCP) or the Fenna-Matthews-Olson (FMO) complex, we also discuss the properties of large, photosynthetic reaction centers (RCs) and Photosystem I (PSI)-both prokaryotic PSI core complexes and eukaryotic PSI supercomplexes with attached antenna clusters (PSI-LHCI)-deposited on SIF substrates.
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