- 标题
- 摘要
- 关键词
- 实验方案
- 产品
-
Temperature-dependent photoluminescence of pure and Mn-doped CsPbCl3 nanocrystals
摘要： Temperature-dependent photoluminescence (PL) properties of Mn-doped CsPbCl3 nanocrystals (NCs) are studied and compared with pure CsPbCl3 NCs by use of steady-state and time-resolved PL spectroscopies. The intrinsic exciton PL of the CsPbCl3 NCs locates at the wavelength range from 405 to 410 nm. The PL intensity in this range decreases rapidly, and the bandgap and linewidth become wider with rising temperature from 78 to 350 K. It is found that the exciton PL shows biexponential kinetics. The short-lived emission is ascribed to the surface trapping state recombination in NCs that has a photoinduced trapped pathway and a temporally resolved peak shift. The long-lived component is due to the band-edge excitonic recombination. Mn dopant open a new emission window at the wavelength range from 560 to 680 nm, of which intensity increases from 140 to 270 K, and then decreases with rising temperature up to 350 K. This unusual temperature dependence is ascribed to the thermal-assisted transition from the excitonic state of NCs to the 4T1 energy level of Mn2+. This work shows the potential of transition metal element doped perovskite NCs that can take advantage of the coupling between excitons and the d electrons of the dopants for expanded functionalities, such as temperature sensor and light-emitting diode.
关键词： Photoluminescence,Band-edge exciton,CsPbCl3,Mn-doped,Nanocrystals
更新于2025-11-25 10:30:42
-
Building Intermixed Donor-Acceptor Architectures for Water-Processable Organic Photovoltaics
摘要： A modified synthesis method for aqueous nanoparticle printing inks, based upon vacuum-assisted solvent removal, is reported. Poly(3-hexylthiophene) : phenyl C61 butyric acid methyl ester nanoparticle inks were prepared via this modified miniemulsion method; leading to both an improvement in photoactive layer morphology and a substantial reduction in the ink fabrication time. A combination of UV-visible spectroscopy, photoluminescence spectroscopy and scanning transmission X-ray microscopy measurements revealed a nanoparticle morphology comprised of highly intermixed donor-acceptor domains. Consistent with these measurements, dynamic mechanical thermal analysis of the nanoparticles showed a glass transition temperature (Tg) of 104 °C, rather than a pure polymer phase or pure fullerene phase Tg. Together the spectroscopy, microscopy and thermomechanical data indicate that rapid solvent removal generates a more blended nanoparticle morphology. As such, this study highlights a new experimental lever for optimising nanostructure in the photoactive layer of nanoparticulate organic photovoltaic devices by enabling highly intermixed donor-acceptor architectures to be built from customised nanoparticulate inks.
关键词： organic photovoltaic,scanning transmission X-ray microscopy,morphology,colloidal inks,exciton dissociation,Nanostructure,eco-friendly processing
更新于2025-11-19 16:46:39
-
Excellent exciton luminescence of CsPbI3 red quantum dots in borate glass
摘要： We have fabricated CsPbI3 perovskite quantum dots in a borate glass by melt-quenching technique. Three representative samples with different treatment conditions are investigated. As treatment condition enhances, energy gap is extracted as 1.75-1.76eV, and photoluminescence peak is adjustable from 675 to 691nm. Full width at half-maximum (FWHM) varies from 43 to 37 nm. PL intensity first increases and then decreases with increasing excitation wavelength, but the peak wavelength and line-shape are independent. High PLQY values of 23.8%-61.4% are obtained. The high PLQY values are attributed to good crystal quality and less energy dissipation. PL lifetime is fitted as 24.0-28.2ns and 100.2-123.0ns for short and long lifetime components in bi-exponential function. For temperature from 25 to 125 oC, PL intensity decreases, but it is reversible. Exciton binding energy is extracted in the level of 375-454meV. The FWHM broadening from 39 to 49nm and peak blue-shift from 690 to 685nm are investigated.
关键词： Photoluminescence quantum yield,Lifetime,CsPbI3,Temperature dependence,Quantum dots glass,Exciton
更新于2025-11-14 15:23:50
-
Effect of exciton diffusion on the triplet-triplet annihilation rate in organic semiconductor host-guest systems
摘要： We study the contribution of triplet exciton diffusion to the efficiency loss resulting from F?rster-type triplet-triplet annihilation (TTA) in organic phosphorescent semiconductor host-guest systems, using kinetic Monte Carlo (KMC) simulations. Our study focusses on diffusion due to F?rster-type guest-guest transfer, but includes also a comparison with simulation results for the case of Dexter-type guest-guest transfer. The simulations are carried out for a wide range of F?rster radii, and for guest concentrations up to 100 mol%, with the purpose to support analyses of time-resolved photoluminescence experiments probing TTA. We find that the relative contribution of diffusion to the TTA-induced efficiency loss may be deduced quite accurately from a quantitative experimental measure for the shape of the time-dependent photoluminescence intensity, the so-called r ratio. For small guest concentrations and F?rster radii that are most relevant to organic light-emitting diodes (OLEDs), the diffusion contribution is in general quite small. Under these weak-diffusion conditions, the absolute diffusion contribution to the TTA-induced efficiency loss can be understood quantitatively using a capture radius formalism. The effective guest-guest diffusion coefficient that follows from the TTA simulations, using the capture radius formalism, agrees well with the diffusion coefficient that follows from direct KMC diffusion simulations. The simulations reveal that the diffusion coefficient is strongly affected by the randomness of the distribution of guest molecule locations.
关键词： OLEDs,photoluminescence,kinetic Monte Carlo simulations,Dexter transfer,organic semiconductors,triplet-triplet annihilation,exciton diffusion,host-guest systems,F?rster transfer
更新于2025-09-23 15:23:52
-
Projector-based renormalization approach to electron-hole-photon systems in their nonequilibrium steady state
摘要： We present an extended version of the projector-based renormalization method that can be used to address not only equilibrium but also nonequilibrium situations in coupled fermion-boson systems. The theory is applied to interacting electrons, holes, and photons in a semiconductor microcavity, where the loss of cavity photons into vacuum is of particular importance. The method incorporates correlation and fluctuation processes beyond mean-field theory in a wide parameter range of detuning, Coulomb interaction, light-matter coupling, and damping, even in the case when the number of quasiparticle excitations is large. This enables the description of exciton and polariton formation and their possible condensation through spontaneous phase symmetry breaking by analyzing the ground-state, steady-state, and spectral properties of a rather generic electron-hole-photon Hamiltonian, which also includes the coupling to two fermionic baths and a free-space photon reservoir. Thereby, the steady-state behavior of the system is obtained by evaluating expectation values in the long-time limit by means of the Mori-Zwanzig projection technique. Tracking and tracing different order parameters, the fully renormalized single-particle spectra and the steady-state luminescence, we demonstrate the Bose-Einstein condensation of excitons and polaritons and its smooth transition when the excitation density is increased.
关键词： exciton condensation,nonequilibrium steady state,semiconductor microcavity,projector-based renormalization method,electron-hole-photon systems,Bose-Einstein condensation,polariton condensation
更新于2025-09-23 15:23:52
-
Ab initio model for the chlorophyll-lutein exciton coupling in the LHCII complex
摘要： 2A_g^- state of lutein plays a crucial role in photoprotection of higher plants. Due to its multiconfigurational nature, accurate description of this electronic state and respective transition properties is a formidable task. In this paper, applicability of various CASSCF and RASSCF formulations for description of the 2A_g^- state is discussed. It is shown that inclusion of the entire π-system of lutein into the active space is required for accurate calculation of transition properties. Exciton coupling in the chlorophyll-lutein dimer involved in non-photochemical quenching in the LHCII complex was calculated to provide a connection between pigment interactions and non-photochemical quenching regulation.
关键词： non-photochemical quenching,MCSCF,Xanthophyll,lutein,exciton coupling,LHCII
更新于2025-09-23 15:23:52
-
Tuning the excitonic properties of ZnO:Sn thin films
摘要： The effects of Sn doping, deposition temperature, and post-annealing treatment on the excitonic behavior of ZnO:Sn (SZO) thin films deposited by dc-unbalanced magnetron sputtering have been studied. Sn doping induces the decrease of grain size and promotes the formation of oxygen vacancy-related trap states as indicated by A1 LO mode in Raman spectra and green emission in photoluminescence spectra. Using a critical point analysis of the dielectric functions from spectroscopic ellipsometry data analysis, Sn doping blueshifts the excitonic absorption and decreases the exciton lifetime via screening the electron-hole Coulomb interaction. By varying the deposition temperature from room temperature up to 300 °C (SZO-3), there is no change in excitonic absorption. Then, annealing of SZO-3 at 600 °C under oxygen environment (SZO-6) strongly improves the excitonic absorption as well as its lifetime. Critical point analysis on SZO-6 sample clearly reveals the excitonic transition at 3.38 eV and exciton-phonon complexes at 3.66 eV. Thus, the result is important to improve the functionality of doped ZnO with strong excitonic absorption for optoelectronic applications.
关键词： Annealing,Dc-unbalanced magnetron sputtering,Exciton,Thin films,Sn doped ZnO
更新于2025-09-23 15:23:52
-
Silk Fibroin-Based Films Enhance Rhodamine 6G Emission in the Solid State: A Chemical-Physical Analysis of their Interactions for the Design of Highly Emissive Biomaterials
摘要： Described herein is the preparation of dye-doped films employing silk fibroin (SF) as a biomaterial, capable of preserving the optical properties of the monomeric dye in the solid state, a critical requisite for optical and biolaser applications. A comprehensive physical–chemical characterization is reported for SF films doped with Rhodamine 6G, an ideal candidate for photonics and optoelectronics. Fourier transform infrared spectroscopy (FTIR), circular dichroism (CD) and X-Ray diffraction (XRD) provide information on SF secondary conformation in the presence of rhodamine. UV–vis absorption spectra and exciton CD inform on the structure of encapsulated rhodamine, while changes in dye photophysical properties illuminate the molecular mechanism of the involved host–guest interactions. SF host environment inhibits rhodamine dimer formation, indicating that SF is an optimum matrix to keep rhodamine essentially monomeric at concentrations as high as 7 mm in the film. The relevant optical properties of these films and the easiness of their preparation, make these systems optimal candidates for innovative photonic technologies.
关键词： FTIR,silk fibroin,dye-doped biomaterials,exciton coupled CD,fluorescence
更新于2025-09-23 15:23:52
-
Suppressed Triplet Exciton Diffusion Due to Small Orbital Overlap as a Key Design Factor for Ultralong-Lived Room-Temperature Phosphorescence in Molecular Crystals
摘要： Persistent room-temperature phosphorescence (RTP) under ambient conditions is attracting attention due to its strong potential for applications in bioimaging, sensing, or optical recording. Molecular packing leading to a rigid crystalline structure that minimizes nonradiative pathways from triplet state is often investigated for efficient RTP. However, for complex conjugated systems a key strategy to suppress the nonradiative deactivation is not found yet. Here, the origin of small rates of a nonradiative decay process from triplet states of conjugated molecular crystals showing RTP is reported. Optical microscopy analysis showed that, despite a favorable molecular stacking, an aromatic crystal with strong RTP is characterized by small diffusion length and small values of the diffusion coefficient of triplet excitons. Quantum chemical calculations reveal a large overlap between the lowest unoccupied molecular orbitals but very small overlap between the highest occupied molecular orbitals (HOMOs). Inefficient electron exchange caused by the small overlap of HOMOs prevents triplet excitons from diffusing over long distances and consequently from quenching at defect sites inside the crystal or at the crystal surface. These results will allow design of comprehensive molecular structures to obtain molecular solids with more efficient RTP.
关键词： suppressed nonradiative rate,persistent room-temperature phosphorescence,triplet exciton diffusion,molecular orbital overlap,fluorescence microscopy
更新于2025-09-23 15:23:52
-
Anisotropic Circular Dichroism of Light-Harvesting Complex II in Oriented Lipid Bilayers: Theory Meets Experiment
摘要： Anisotropic circular dichroism (ACD) spectroscopy of macroscopically aligned molecules reveals additional information about their excited states that is lost in the CD of randomly-oriented solutions. ACD spectra of light-harvesting complex II (LHCII)—the main peripheral antenna of photosystem II in plants—in oriented lipid bilayers, were recorded from the far-UV to the visible wavelength region. The ACD spectra show a drastically enhanced magnitude and level of detail compared to the isotropic CD spectra, resolving a greater number of bands and weak optical transitions. Exciton calculations show that the spectral features in the chlorophyll Qy region are well reproduced by an existing Hamiltonian for LHCII, providing further evidence for the identity of energy sinks at chlorophylls a603 and a610 in the stromal layer and chlorophylls a604 and a613 in the luminal layer. We propose ACD spectroscopy to be a valuable tool linking the three-dimensional structure and the photophysical properties of pigment–protein complexes.
关键词： optical spectroscopy,photosynthetic complexes,model membranes,oriented CD,excitonic CD,exciton theory
更新于2025-09-23 15:23:52