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Energy-Dependent Spectral Analysis of Photon-Assisted Carrier Transport at Resonance in Graphene Oxide
摘要： Owing to its excellent optoelectronic properties, graphene oxide (GO) has been investigated for use in optoelectronic devices in the past decade. GO-based devices such as photodetectors are expected to show remarkable high-frequency transmittances. However, the band properties are typically investigated using optical measurement methods, and these techniques have limitations on the maximum light intensity that can be employed and require the use of filters. To overcome these problems, high-frequency electrical measurements are applied to use resonance under illumination. The measured resonance signal probes the band properties of GO, while the electromagnetic radiation excites the samples. The spectral analysis of GO-based optoelectronic devices reveals the relationship between the band properties and the photon energy. Moreover, the resistance of GO, which is measured via the de-embedding process, is related to the band levels and photon energies. Thus, spectral analysis can be used to probe not only the photodetector properties of GO-based devices but also their band structure.
关键词： graphene oxide,resonance,photon,high frequency,energy levels
更新于2025-09-23 15:22:29
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Perylene Diimide Based Conjugated Polymers for All Polymer Solar Cells
摘要： For recent decades, non-fullerene acceptors (NFAs) are undergoing rapid development and emerging as a hot area in the field of organic solar cells. Among the high performance nonfullerene acceptors, aromatic diimide based electron acceptors remain to be the highly promising systems. This review discusses the important progress of perylene diimide (PDI)-based polymers as nonfullerene acceptors (NFAs) in all polymer solar cells (all-PSCs) since 2014. The relationship between structure and property, matching aspects between donors and acceptors and device fabrications are unveiled from a synthetic chemist perspective.
关键词： nonfullerene acceptors (NFA),all-polymer solar cells (all-PSCs),energy levels,perylene diimide (PDI),PCE
更新于2025-09-23 15:21:01
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Nonlinear Optics || Quantum-Mechanical Theory of the Nonlinear Optical Susceptibility
摘要： In this chapter, we use the laws of quantum mechanics to derive explicit expressions for the nonlinear optical susceptibility. The motivation for obtaining these expressions is at least three-fold: (1) these expressions display the functional form of the nonlinear optical susceptibility and hence show how the susceptibility depends on material parameters such as dipole transition moments and atomic energy levels, (2) these expressions display the internal symmetries of the susceptibility, and (3) these expressions can be used to make predictions of the numerical values of the nonlinear susceptibilities. These numerical predictions are particularly reliable for the case of atomic vapors, because the atomic parameters (such as atomic energy levels and dipole transition moments) that appear in the quantum-mechanical expressions are often known with high accuracy. In addition, since the energy levels of free atoms are very sharp (as opposed to the case of most solids, where allowed energies have the form of broad bands), it is possible to obtain very large values of the nonlinear susceptibility through the technique of resonance enhancement. The idea behind resonance enhancement of the nonlinear optical susceptibility is shown schematically in Fig. 3.1.1 for the case of third-harmonic generation. In part (a) of this figure, we show the process of third-harmonic generation in terms of the virtual levels introduced in Chapter 1. In part (b) we also show real atomic levels, indicated by solid horizontal lines. If one of the real atomic levels is nearly coincident with one of the virtual levels of the indicated process, the coupling between the radiation and the atom becomes particularly strong and the nonlinear optical susceptibility becomes large.
关键词： resonance enhancement,quantum mechanics,nonlinear optical susceptibility,third-harmonic generation,dipole transition moments,atomic energy levels
更新于2025-09-23 15:21:01
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On the use of multiple stacked active layers in organic photovoltaic cells
摘要： In the field of organic photovoltaic cells (OPVs), ternary planar heterojunction allows widening absorption range. Optimization of the energy levels at the organic interfaces is the first task to achieve in order to obtain OPVs with high efficiency. In ternary OPVs, carrier mobility, charge transfer and presence of energy transfer are determinant. Here, we compare the performances of different, binary (electron donor/fullerene) and ternary (electron donor/ambipolar material/fullerene) combinations of small organic molecules in planar heterojunction (PHJ) cells. We chose the different ED molecules in order to investigate the different possible band scheme alignments. The study shows that if the open circuit voltage (Voc) is limited by the energy levels of the outer layers, i.e. the difference between the lowest unoccupied molecular orbital (LUMO) of the electron acceptor and the highest occupied molecular orbital (HOMO) of the outer electron donor layer, the energy loss can be smaller than 0.2 eV. If efficient ternary OPVs need global energy offset higher than the exciton energy to separate the charges of the exciton, the distribution of this offset between DLUMO and DHOMO is not critical. The mobility value of the carriers in the intercalated layer is determinant in obtaining performance of OPVs. Overlap between the photoluminescence of ED and the optical absorption of EDA is primordial for good energy transfer. The highest OPV efficiency improvement is obtained with organic materials such as ED and EDA that have the same HOMO and similar hole mobility which give homogeneous thin layers.
关键词： organic photovoltaic cells,energy levels,energy transfer,carrier mobility,charge transfer,ternary planar heterojunction
更新于2025-09-23 15:19:57
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Development of low laser energy levels in small-incision lenticule extraction
摘要： Purpose: To evaluate the outcomes of 4 low laser energy levels after small-incision lenticule extraction (SMILE) surgery. Setting: Zhongshan Ophthalmic Center, Guangzhou, China. Design: Prospective randomized clinical trial. Methods: This study evaluated consecutive patients who had SMILE to correct myopia or myopia with astigmatism. Eyes were placed into groups based on the laser energy used during surgery (ie, 105 nJ, 110 nJ, 115 nJ, or 120 nJ). All patients had a thorough ophthalmic examination preoperative and at 4 timepoints over 3 months postoperatively. Black areas and surface regularity of the extracted lenticules were observed and evaluated qualitatively and quantitatively. Results: The study comprised 124 eyes of 62 patients (40 women, 22 men), with 31 eyes in each laser energy group. The incidence of black areas was 45.16% (14 of 31 eyes), 12.90% (4 of 31 eyes), 16.13% (5 of 31 eyes), and 12.90% (4 of 31 eyes) for 105 nJ, 110 nJ, 115 nJ, and 120 nJ, respectively. The mean time for lenticule creation was the longest in the 105 nJ group (P = .015). The greatest increase in corneal thickness postoperatively occurred with 105 nJ (P < .05). Regression was highest in the 105 nJ group at 3 months (P < .01). However, corneal horizontal coma (C8) was lowest in the 105 nJ group at 1 week (P = .032). The lenticular surface in the 110 nJ group was the smoothest (P = .011). All contrast sensitivity values varied with time and recovered to preoperative levels by 1 week or 1 month. In all eyes, the uncorrected distance visual acuity and corrected distance visual acuity were good, with no statistically significant differences between the 4 energy groups. Conclusions: The 105 nJ group, in which the lowest energy was used, had the highest risk for black areas, serious postoperative corneal edema, and a significant healing response.
关键词： small-incision lenticule extraction,laser energy levels,black areas,SMILE,corneal edema
更新于2025-09-23 15:19:57
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Lasing in a coupled hybrid double quantum dot-resonator system
摘要： We theoretically investigate the possibility of lasing in an electromagnetic resonator coupled to a voltage-biased hybrid double quantum dot comprised of a double quantum dot tunnel coupled simultaneously to a normal metal and a superconducting lead. Using a unitary transformation, we derive a resonator-double quantum dot interaction Hamiltonian in the rotating-wave approximation which reveals the fact that lasing in this system is mediated by electron transitions between Andreev energy levels in the system’s density of states. Moreover, by employing a Markovian master equation incorporating dissipation effects for the electronic and photonic degrees of freedom, we numerically calculate the steady-state reduced density matrix of the system from which we determine the average photon number and its statistics in the resonator in various parameter regimes. We ?nd that at some appropriate parameter con?gurations, lasing can be considerably enhanced due to the possibility of electron transitions between multiple Andreev levels in the system.
关键词： lasing,Andreev energy levels,hybrid double quantum dot,electromagnetic resonator,Markovian master equation
更新于2025-09-23 15:19:57
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Redefinition the quasi-Fermi energy levels separation of electrons and holes inside and outside quantum wells of GaN based multi-quantum-well semiconductor laser diodes
摘要： Both accurate experiments and a self-consistent theoretical simulation using the near-ABC or ab initio method have uncovered the anomalous changes in the junction voltage (Vj ) of GaN-based lasers (Li et al 2013 Appl. Phys. Lett. 102 123501, Feng et al 2018 J. Phys. D: Appl. Phys. 51 095102 and Feng et al Appl. Phys. B 124 39). Here, further accurate emission spectral characteristics and band-gap simulation of a GaN based laser diodes (LDs) confirmed that previous researchers may have confused the junction voltage (Vj ) and the separation between the two Fermi levels of electrons and holes in the active region divided by the electronic charge (ΔEf /e). For the multiple-quantum wells (MQWs), there are obvious differences between them. For an ideal GaN-based LDs, despite the increase in junction voltage, physical quantities including the separation between the two Fermi levels of electrons and holes in the MQW region, and the optical net gain remain unchanged beyond the threshold region after an unpredictable sharp increase in the threshold region.
关键词： multi-quantum-well (MQW),steady state,junction voltage,quasi-Fermi energy levels separation,GaN based laser diodes (LD)
更新于2025-09-19 17:13:59
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Photovoltaic effect in bulk heterojunction system with glass forming indandione derivative DMABI-6Ph
摘要： The aim of the work is to evaluate possible use of 2-[[4-(bis(2-trityloxyethyl)amino)phenyl]methylene]indane-1,3-dione (DMABI-6Ph) as light absorbing material for solar cells. DMABI-6Ph is a perspective material due to its good photoelectrical, thermal and chemical properties. The main advantage of DMABI-6Ph is its ability to form amorphous films by wet-casting methods thus allowing using the compound in organic solar cells made from solution. For now most popular materials for solution processable solar cells are polymer P3HT and fullerene derivative PCBM, but lot of investigations are in the field of new low molecular weight materials to replace the polymer. Photoelectrical measurements were made to determine molecule ionization and electron affinity levels of DMABI-6Ph. Difference of 2.06 eV between DMABI-6Ph ionization level and PCBM affinity level was obtained. Accordingly open circuit voltage of system DMABI-6Ph:PCBM was measured up to 0.78 V. The best power conversation efficiency was 0.11 % for the DMABI-6Ph:PCBM mass fraction 2:1. Limiting factor for high efficiency could be low charge carrier mobility which can be increase by additional DMABI-6Ph modification.
关键词： energy levels,glass forming structure,bulk heterojunction,indandione group,power conversion efficiency
更新于2025-09-12 10:27:22
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A Novel Carbazole Based Nonfullerene Acceptor for High‐Efficiency Polymer Solar Cells
摘要： Two novel nonfullerene acceptors 4TFIC-4F and 4TCIC-4F are designed based on fluorene and carbazole. Compared with 4TFIC-4F, 4TCIC-4F exhibited higher LUMO level and narrower optical bandgap. Therefore, Polymer solar cells based on PBDB-T-2Cl:4TCIC-4F achieve a high power conversion efficiency of 13.02%, which is the highest value for the carbazole-containing nonfullerene acceptors based devices.
关键词： Morphology,Nonfullerene acceptors,Donor core,Energy levels,Polymer solar cells
更新于2025-09-11 14:15:04
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, and HD
摘要： We calculate the nonadiabatic relativistic correction to rovibrational energy levels of H2, D2, and HD molecules using the nonadiabatic perturbation theory. This approach allows one to obtain nonadiabatic corrections to all the molecular levels with the help of a single effective potential. The obtained results are in very good agreement with the previous direct calculation of nonadiabatic relativistic effects for dissociation energies and resolve the reported discrepancies of theoretical predictions with recent experimental results.
关键词： nonadiabatic perturbation theory,nonadiabatic relativistic correction,HD,D2,H2,rovibrational energy levels
更新于2025-09-10 09:29:36