Harvesting electrical energy using plasmon-enhanced light pressure in a platinum cut cone
Optics Express Optica 29:22 (2021) 35161-35171
Abstract:
We have designed a method of harvesting electrical energy using plasmon-enhanced light pressure. A device was fabricated as a cut cone structure that optimizes light collection so that the weak incident light pressure can be sufficiently enhanced inside the cut cone to generate electrical energy. An increase in the device's current output is a strong indication that the pressure of incident light has been enhanced by the surface plasmons on a platinum layer inside the cut cone. The electrical energy harvested in a few minutes by irradiating pulsed laser light on a single micro device was possible to illuminate a blue LED.An insight study into the parameters altering the emission of a covalent triazine framework
Journal of Materials Chemistry C Materials for optical and electronic devices Royal Society of Chemistry 9 (2021) 13770-13781
Abstract:
Covalent triazine frameworks (CTFs) synthesized through nucleophilic substitution of 4,4’ bipyridine on the carbon atoms of cyanuric chloride were studied as fluorescent sensors. The band gap of the materials was calculated to be 2.95 eV from diffuse reflectance measurements, while from the adsorption in aqueous dispersions, we obtained the value of 3.7 eV. A partial exfoliation of the layered CTFs in water or tetrahydrofuran led to different morphologies, increased emission lifetime and fluorescence quantum yield. The pattern of their light emission properties in combination with their redox states was defined with the addition of a series of acidic and basic analytes. Another unique aspect of these semiconducting materials is the induced aggregation and the subsequent enhancement of emission under ultraviolet illumination.Quantification of temperature-dependent charge separation and recombination dynamics in non-fullerene organic photovoltaics
Advanced Functional Materials Wiley 31:48 (2021) 2107157
Abstract:
Transient optical spectroscopy is used to quantify the temperature-dependence of charge separation and recombination dynamics in P3TEA:SF-PDI2 and PM6:Y6, two non-fullerene organic photovoltaic (OPV) systems with a negligible driving force and high photocurrent quantum yields. By tracking the intensity of the transient electroabsorption response that arises upon interfacial charge separation in P3TEA:SF-PDI2, a free charge generation rate constant of ≈2.4 × 1010 s−1 is observed at room temperature, with an average energy of ≈230 meV stored between the interfacial charge pairs. Thermally activated charge separation is also observed in PM6:Y6, and a faster charge separation rate of ≈5.5 × 1010 s−1 is estimated at room temperature, which is consistent with the higher device efficiency. When both blends are cooled down to cryogenic temperature, the reduced charge separation rate leads to increasing charge recombination either directly at the donor-acceptor interface or via the emissive singlet exciton state. A kinetic model is used to rationalize the results, showing that although photogenerated charges have to overcome a significant Coulomb potential to generate free carriers, OPV blends can achieve high photocurrent generation yields given that the thermal dissociation rate of charges outcompetes the recombination rate.Resonantly pumped bright-triplet exciton lasing in cesium lead bromide perovskites
ACS Photonics American Chemical Society 8:9 (2021) 2699-2704
Abstract:
The surprising recent observation of highly emissive triplet-states in lead halide perovskites accounts for their orders-of-magnitude brighter optical signals and high quantum efficiencies compared to other semiconductors. This makes them attractive for future optoelectronic applications, especially in bright low-threshold nanolasers. While nonresonantly pumped lasing from all-inorganic lead-halide perovskites is now well-established as an attractive pathway to scalable low-power laser sources for nano-optoelectronics, here we showcase a resonant optical pumping scheme on a fast triplet-state in CsPbBr<sub>3</sub> nanocrystals. The scheme allows us to realize a polarized triplet-laser source that dramatically enhances the coherent signal by 1 order of magnitude while suppressing noncoherent contributions. The result is a source with highly attractive technological characteristics, including a bright and polarized signal and a high stimulated-to-spontaneous emission signal contrast that can be filtered to enhance spectral purity. The emission is generated by pumping selectively on a weakly confined excitonic state with a Bohr radius ∼10 nm in the nanocrystals. The exciton fine-structure is revealed by the energy-splitting resulting from confinement in nanocrystals with tetragonal symmetry. We use a linear polarizer to resolve 2-fold nondegenerate sublevels in the triplet exciton and use photoluminescence excitation spectroscopy to determine the energy of the state before pumping it resonantly.Exciton dynamics in monolayer graphene grown on a Cu(111) surface
npj 2D Materials and Applications Springer Nature 5:1 (2021) 69