- 标题
- 摘要
- 关键词
- 实验方案
- 产品
-
10.13% Efficiency Alla??Polymer Solar Cells Enabled by Improving the Optical Absorption of Polymer Acceptors
摘要： All-polymer solar cells (all-PSCs) are one of the most promising flexible and wearable energy generators due to their excellent morphology stability and mechanical robustness. However, it has been limited light absorption capacity for most polymer acceptors that hinders the improvement of power conversion efficiency (PCE) of all-PSCs. Herein, by simultaneously increasing the conjugation of the acceptor unit and enhancing the electron-donating ability of the donor unit, a novel narrow-bandgap polymer acceptor PF3-DTCO based on a A-D-A-structured acceptor unit ITIC16 and a carbon-oxygen (C-O)-bridged donor unit DTCO was developed. Extended conjugation of the acceptor units from IDIC16 to ITIC16 result in a red-shifted absorption spectrum and improved absorption coefficient without significant LUMO level reduction. Moreover, in addition to further broadening the absorption spectrum by the enhanced intramolecular charge transfer effect, the introduction of C-O-bridges into donor unit improves the absorption coefficient and electron-mobility, as well as optimizes the morphology and molecular order of active layers. As a result, the PF3-DTCO achieved a higher PCE of 10.13% with a higher short-circuit current density (Jsc) of 15.75 mA cm-2 in all-PSCs compared to its original polymer acceptor PF2-DTC (PCE=8.95% and Jsc=13.82 mA cm-2). Our work provides a promising method to construct high-performance polymer acceptors with excellent optical absorption for efficient all-PSCs.
关键词： optical absorption,all-polymer solar cells,polymer acceptor,carbon-oxygen-bridging,power conversion efficiency
更新于2025-09-23 15:19:57
-
Composition and size controlled I-V-VI semiconductor nanocrystals
摘要： Non-isovalent ternary and quaternary semiconductors (i.e., having two or more cations with different valence) have unique structural and electronic properties that are leveraged in photovoltaic, thermoelectric, and phase-change memory devices. Making these complex semiconductors in the form of colloidal nanocrystals imparts size-dependent properties and solution processability. Here, we present results on I‐V‐VI group colloidal nanocrystals. We focus on achieving sub-10 nm sizes for a wide range of I-V-VI selenide nanocrystals, including AgSbSe2, AgSb2Se3, CuSbSe2, Cu3SbSe4, AgBiSe2, and CuBiSe2. To highlight one possible application for these I-V-VI colloidal nanomaterials, we analyze the optical absorption and show that through composition and size control, this class of materials offers bandgaps in the mid- to near-IR. Absorption coefficients of AgSbSe2, CuSbSe2, and Cu3SbSe4 nanocrystals are on par with or higher than the well-studied PbS nanocrystals highlighting their potential for devices such as solar cells, (mid-)infrared photodetectors, and near-infrared bio-imaging systems.
关键词： solar cells,optical absorption,bio-imaging systems,colloidal nanocrystals,infrared photodetectors,mid- to near-IR,I-V-VI semiconductor nanocrystals,bandgaps
更新于2025-09-23 15:19:57
-
Near-infrared absorption enhancement for perovskite solar cells via the rear grating design
摘要： Optical management and design is one of the most effective methods to unlock the full potential of photocurrent density and power conversion efficiency for perovskite solar cells (PSCs). However, the common-used optical designs are still limited by the near-infrared response. Here, we proposed an effective optical structure in PSCs by texturing the rear-side perovskite layer with a rectangular grating to promote the optical response in the near-infrared region. Through the comprehensive numerical simulations, the new design under the optimized structural configuration shows an improved photocurrent density, i.e., from 22.75 (flat structure) to 23.72? mA/cm2. We confirm that the optical absorption enhancement occurs at the near-infrared region by the wavelength-dependent absorption and reflection spectra. Besides, the light-trapping mechanism was clarified by the comprehensive analysis of the electric field distributions. Moreover, PSCs having the rear-grating design demonstrate the superior optical performance compared to that of flat design in the varied incident angles. Our simulation results displayed in this study provide an easy scheme to promote the optical absorption in near-infrared region.
关键词： Near-infrared light,Rear grating,Perovskite solar cells,Optical absorption
更新于2025-09-23 15:19:57
-
Visible and IR luminescence of complex centers created by thermo-optical treatment in anion-deficient corundum
摘要： To verify the possibility of creating complex centers in anion-deficient corundum crystals (α-Al2O3-δ) by special thermo-optical treatment, optical absorption (OA) and photoluminescence (PL) spectra have been studied at nitrogen and helium temperatures. At low temperatures, the OA and PL bands recorded in the visible and near infrared (NIR) regions displayed zero-phonon lines and phonon-assisted lines. Their comparison with analogous OA and PL bands in neutron-irradiated stoichiometric α-Al2O3 samples revealed full similarity between their vibronic structures. These findings are additional evidence to support the possibility of generating non-radiatively in α-Al2O3-δ complex centers radiating in the visible and NIR regions. The results of the study will enable the applications of corundum detector and laser technologies to be extended.
关键词： Anion-deficient corundum,Photoluminescence,Optical absorption,Vibronic structure,Formation of complex defects,Thermo-optical treatment
更新于2025-09-19 17:15:36
-
Silicon nitride and silica quarter-wave stacks for low-thermal-noise mirror coatings
摘要： This study investigates a multilayer high reflector with new coating materials for next-generation laser interferometer gravitational wave detectors operated at cryogenic temperatures. We use the plasma-enhanced chemical vapor deposition method to deposit amorphous silicon nitride and silica quarter-wave high-reflector stacks and studied the properties pertinent to the coating thermal noise. Room- and cryogenic-temperature mechanical loss angles of the silicon nitride and silica quarter-wave bilayers are measured using the cantilever ring-down method. We show, for the first time, that the bulk and shear loss angles of the coatings can be obtained from the cantilever ring-down measurement, and we use the bulk and shear losses to calculate the coating thermal noise of silicon nitride and silica high-reflector coatings. The mechanical loss angle of the silicon nitride and silica bilayer is dispersive with a linear weakly positive frequency dependence, and, hence, the coating thermal noise of the high reflectors show a weakly positive frequency dependence in addition to the normal 1/sqrt(f) dependence. The coating thermal noise of the silicon nitride and silica high-reflector stack is compared to the lower limit of the coating thermal noise of the end test mirrors of ET-LF, KAGRA, LIGO Voyager, and the directly measured coating thermal noise of the current coatings of Advanced LIGO. The optical absorption of the silicon nitride and silica high reflector at 1550 nm is 45.9 ppm. Using a multimaterial system composed of seven pairs of ion-beam-sputter deposited Ti:Ta2O5 and silica and nine pairs of silicon nitride and silica on a silicon substrate, the optical absorption can be reduced to 2 ppm, which meets the specification of LIGO Voyager.
关键词： quarter-wave stacks,silica,silicon nitride,gravitational wave detectors,thermal noise,mechanical loss,cryogenic temperatures,optical absorption,mirror coatings
更新于2025-09-19 17:15:36
-
Optical absorption in complexes of abasic DNA with noble-metal nanoclusters by first principles calculations
摘要： Optical absorption in complexes of abasic DNA with noble-metal nanoclusters by first principles calculations. Abasic sites (AP site) in a DNA duplex have been experimentally used to produce fluorescent Ag nanoclusters (NC) with a small number of atoms (n ≤ 6). These AP-DNA:NC complexes act as biological markers that help to locate genes associated with diseases related to single nucleotide polymorphisms (SNP), for example. Abasic sites are the most common SNP genetic variation, and their detection may help predict a host of genetically determined diseases. In this work, we report a theoretical study of the optical absorption spectra of AP-DNA:Ag4 and AP-DNA:Au4 complexes using a fully ab initio methodology. We consider several different base environments for the noble-metal nanocluster occupying the AP site, and compute the absorption spectra of sixteen AP-DNA:Ag4 and sixteen AP-DNA:Au4 complexes. We find that optical absorption in the AP-DNA:Ag4 complexes tends to concentrate in the green-to-violet range of frequencies (2.50 eV ≤ ?ω ≤ 3.2 eV) and that AP-DNA:Au4 complexes display absorption peaks in the violet-to-ultraviolet interval (?ω ≥ 3.0 eV). An analysis of the optical absorption mechanisms in these AP-DNA:NC complexes shows that they can be of local, charge-transfer, or hybrid nature, i.e., AP-DNA:NC complexes display the full variety of optical absorption processes in molecular systems. In particular, we identify both charge-transfer and hybrid processes involving several DNA bases surrounding the NC. Importantly, we find that even sequences where the Ag4 cluster is not in a guanine rich neighborhood display absorption peaks in the visible-light spectrum. Moreover, we obtain that the maximum intensities of the absorption peaks in complexes with pyrimidine vacancies are generally higher than those in complexes with purine vacancies. Regarding the selectivity of single-vacancy AP-DNA to specific noble-metal nanocluster sizes, our calculations show that the four-atom Ag4 (Au4) species fits naturally and binds into the AP-site in a single-vacancy AP-DNA.
关键词： noble-metal nanoclusters,optical absorption,first principles calculations,abasic DNA,Au4,charge-transfer,hybrid processes,Ag4
更新于2025-09-19 17:15:36
-
Ultrafast Charge Carrier Dynamics and Nonlinear Optical Absorption of InP/ZnS Core-Shell Colloidal Quantum Dots
摘要： Understanding of ultrafast carrier dynamics in InP/ZnS colloidal quantum dots (QDs) is essential for their optoelectronic applications. In this paper, we have successfully fabricated high-quality InP/ZnS core-shell QDs with quantum yield (QY) of 47%. Time resolved photoluminescence (TRPL), femtosecond transient absorption (TAS) measurements were performed to characterize the carrier injection, relax and transition process in the InP/ZnS QDs. It is found that the photoexcited carrier first injected to ZnS shell in 2 ps, then relaxed to alloyed layer between ZnS shell and InP core in 7.4 ps, next relaxed to different energy levels in InP core in about 170 ps, finally recombined by charged and neutral excitons transition in 4.1 ns and 26.7 ns, respectively. Additionally, the two-photon absorption (TPA) coefficient obtained from Z-scan measurement indicates that InP/ZnS QDs possess good nonlinearly optical properties. Our research is significant for the improvement and engineering of InP/ZnS QDs based materials for optoelectronic applications.
关键词： quantum dots,InP/ZnS,ultrafast carrier dynamics,nonlinear optical absorption,optoelectronic applications
更新于2025-09-19 17:13:59
-
Terahertz intersubband transitions in GaAsBi/AlGaAs single quantum well heterostructure
摘要： GaAsBi/AlGaAs single quantum well conduction band structure, energy levels, and their corresponding wavefunctions have been calculated by solving the Schr?dinger equation. The influences of the heterostructure parameters on the intersubband transition (ISBT) frequency within the terahertz (THz) domain have been investigated. The results show that the quantum well width has a great impact on the THz ISBT frequency. In particular, an ISBT with a frequency of 2.611 THz (10.80?meV) has been obtained for specifically optimized parameters. The study of the intersubband optical absorption coefficient (OAC) was centered in the frequency band of 2 – 14 THz ( ~ 8 – 58 meV), therefore the corresponding results are useful for the optimization of THz detectors. Correspondingly, by changing the thickness of the active layer the number of the OAC peaks has been tuned. The dipole matrix element and the Fermi occupation function have been also studied in detail. Furthermore, the influences coming from the incidence angle on the OAC intensity were numerically investigated. The obtained results could be beneficial for the design and the optimization of devices operating in the THz frequency band.
关键词： GaAsBi quantum well,Terahertz region,Intersubband transitions,Optical absorption coefficient,Incidence angle,Active layer thickness
更新于2025-09-19 17:13:59
-
: Why Sn substitution should be preferred to Pb vacancy for optimum solar cell efficiency
摘要： Methylammonium lead halide (MAPbI3) perovskite has emerged as one of the frontier optoelectronic semiconductors. To avoid lead toxicity, the role of Sn substitution and Pb vacancy (Pb-(cid:2)) are addressed in regulating stability and solar cell ef?ciency of MAPb1?X ?Y SnX (cid:2)Y I3 perovskite using hybrid density functional theory (DFT). The role of spin-orbit coupling (SOC) and the electron’s self-interaction error are examined carefully. We ?nd to reduce the Pb content from pristine MAPbI3, Sn substitution has a more favorable thermodynamic stability than creating Pb-(cid:2). Moreover, on substituting Sn, due to strong s-p and p-p couplings, the lower parts of the conduction band gets shifted downwards, which results in the reduction of the band gap (direct). This further helps us to get a high optical absorption coef?cient (redshifted) and maximum solar cell ef?ciency in MAPb1?X SnX I3 for 0 < X (cid:2) 0.5.
关键词： spin-orbit coupling,MAPbI3,solar cell efficiency,Pb vacancy,thermodynamic stability,Sn substitution,Methylammonium lead halide,hybrid density functional theory,optical absorption coefficient
更新于2025-09-19 17:13:59
-
Enhancement of Emission Intensity in Dy <sup>3+</sup> -Doped ZnO/ZnF <sub/>2</sub> Phosphoborate Glasses for W-LED Materials
摘要： Presently, white light emitting diodes (W-LEDs) were be used to substitute for conventional incandescent and fluorescent lamps due to their advantages; thus, it gets attention to create Dy3+-doped zinc phosphoborate glasses for enhancing better lightness. In this research, the replacing of ZnO by ZnF2 in 49B2O3:30P2O5:(20-x)ZnO:xZnF2:1Dy2O3 glasses, 0 ≤ x ≤ 20 mol% were prepared by melt quenching method and investigated through optical absorption and photoluminescence properties. The absorption results can be used for calculating the Judd-Ofelt (JO) intensity parameters (Ωλ, λ = 2, 4 and 6) and led to predicting the stimulated emission in present glasses. The trend of JO parameters is found to be Ω2 > Ω4 > Ω6 for all glasses. Nevertheless, replacing of ZnF2 does not affect position and intensity of optical absorption of Dy3+-doped glasses, whereas the observed blue (481 nm), yellow (573 nm) and red (662 and 752 nm) emission intensities of photoluminescence spectra rise with ZnF2 contents; the emission intensity at 573 nm for 20ZnF2 show the highest and was higher than 20ZnO around 1.6 times. The emission color of Dy3+-doped zinc phosphoborate glasses has been evaluated with CIE 1931 chromaticity diagram. The results revealed that all glasses emit white light. Hence, these glasses may be suitable candidate for using in W-LED and lighting materials.
关键词： optical absorption,Judd-Ofelt parameters,photoluminescence,ZnF2,W-LEDs,zinc phosphoborate glasses,Dy3+-doped
更新于2025-09-19 17:13:59