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The β-FeSi2 thin film has been applied in the research field of the solar cell,and the thickness of β-FeSi2 absorption layer was chosen through the experiments.However,Up to now neither the optimal thickness of β-FeSi2 absorption layer nor the relationship between the thickness of β-FeSi2 absorption layer and the solar photo wavelength has been theoretically studied.In this paper,the relationship between the thickness of the absorption layer of β-FeSi2 thin film solar cell and the solar photo wavelength is calculated and analyzed by theory.The results show that the thickness of the absorption layer of β-FeSi2 is at least 200 nm when the optical absorption efficiency of the solar energy reaches 90%,and that the optimal thickness range is from 200 nm to 250 nm,and that the optimal wavelength of the photon absorbed by β-FeSi2 thin film solar cell is from 0.46 μm？0.6 μm.Furthermore,two formulas are put forward to indicate the relationship between the thickness of the absorption layer of β-FeSi2 thin film solar ce

Ultrathin cells have gained increasing attention due to their potential for reduced weight, reduced cost and increased flexibility. However, the light absorption in ultrathin cells is usually very weak compared to the corresponding bulk cells. To achieve enhanced photon absorption in ultrathin thermophotovoltaic （TPV） cells, this work proposed a film-coupled metamaterial structure made of nanometer-thick gallium antimonide （GaSh） layer sandwiched by a top one-dimensional （1D） metallic grating and a bottom metal film. The spectral normal absorptance of the proposed structure was calculated using the rigorous coupled-wave algorithm （RCWA） and the absorption enhancement was elucidated to be attributed to the excitations of magnetic polariton （MP）, surface plasmon polariton （SPP）, and Fabry-Perot （FP） resonance. The mechanisms of MP, SPP, and FP were further confirmed by an inductor-capacitor circuit model, disper- sion relation, and phase shift, respectively. Effects of grating period, width, spacer thickness, as well as incidence angle were discussed. Moreover, short-circuit current density, open-circuit voltage, output electric power,and conversion efficiency were evaluated for the ultrathin GaSb TPV cell with a film-coupled metamaterial structure. This work will facilitate the development of next- generation low-cost ultrathin infrared TPV cells.

Two new multibranched thiophene-based triarylamine derivatives with 1,3,5-triazine core are synthesized and characterized. Their one-and two-photon absorption properties and aggregation-induced emission effect have been investigated. Both the STAPA-based compounds are AIE active. The two-photon absorption （2PA） cross sections measured by the open aperture Z-scan technique are determined to be 620 and 1610 GM for STAPA-a and STAPA-b in chloroform,respectively, which dramatically increase with the introduction of alkyl chains. The relationship between their structures and properties on one-and two-photon absorption and aggregation-induced emission is discussed, which allows us to examine the effect of introducing alkyl chains. In addition, solvent effects also show a significant influence on the 2PA cross section. The two compounds with excellent AIE and 2PA properties provide attractive alternatives for the biophotonic materials.

In this study,linear absorption,single-photon excited fluorescence,fluorescence quantum yields,fluorescence lifetime and two-photon excited fluorescence of a series of triphenylamine derivatives （L1,L2,L3 and L4） have been measured.L1 and L3 are D--A type dyes,while L2 and L4 are D--D--A type dyes （D=donor,A=acceptor）.The investigated compounds consist of triphenylamine-bearing donor-substituted and/or systematically extended-conjugated length,which are designed to gain insight into the effect of the ethoxyl unit and-linkage length on the linear and nonlinear optical properties.The influence of solvent polarity on the photophysical properties was investigated.Employing time-dependent density functional theory （TD-DFT） calculations,the structure-property relationships are discussed.

Realizing photon upconversion in nanostructures is important for many next- generation applications such as biological labelling, infrared detectors and solar cells. In particular nanowires are attractive for optoelectronics because they can easily be electrically contacted. Here we demonstrate photon upconversion with a large energy shift in highly n-doped InP nanowires. Crucially, the mechanism responsible for the upconversion in our system does not rely on multi-photon absorption via intermediate states, thus eliminating the need for high photon fluxes to achieve upconversion. The demonstrated upconversion paves the way for utilizing nanowires--with their inherent flexibility such as electrical contactability and the ability to position individual nanowires--for photon upconversion devices also at low photon fluxes, possibly down to the single photon level in optimised structures.

Two novel terpyridine-based chromophores with D-A （D = donor, A = acceptor） structural model containing modified triphenylamine moiety （L1 and L2 ） have been conveniently synthesized via formylation and reduction in satisfactory yields, and fully characterized. The single crystals of them were obtained and determined by X-ray diffraction analysis. The relationships between structure and photophysical properties of the two chromophores were investigated both experimentally and theoretically. The measured maximum TPA cross-sections per molecular weight （δmax /MW） of the chromophores are 0.63 GM/（g mol） （L1） and 0.72 GM/（g mol） （L2）, respectively, in DMF as a high polar solvent. The results indicate that the value of δmax/MW could be well tuned by the intramolecular charge transfer （ICT）, which could be realized by introducing additional elecron-donor/acceptor groups.

We have theoretically investigated two series of cyclometalated Pt（II） complexes, a series [Pt （C, N, N） Cl] and b series [Pt （C, N, Npyrazolyl） Cl]. The geometrical and electronic structures are calculated at the ECP60MWB//6-31G＊（H, C, Cl, N, S） basis set level using DFT method; one-photon absorption （OPA） properties are calculated by using both TDDFT and ZINDO methods and two-photon absorption （TPA） properties are obtained with the ZINDO/SOS method. The resonance integrals parameters （βsp and βd） for Pt are adjusted to -1 and -28.5 eV, respectively, to make max OPA wavelength calculated by ZINDO closest to the experimental data and TDDFT results. The calculated results indicate the molecule 2b （[Pt （Cnaphthyl, N, Npyrazolyl） Cl]） has the biggest potential as outstanding TPA materials because （i） the TPA properties of b series are more outstanding in IR wavelength range, the molecules in b series have good transparencies and possess 1-pyrazolyl-NH that is also available for another metal coordination （e.g., dimerization） and chemical interactions; （ii） when C is CnaphthyI in the C, N, N ligand of cyclometalated Pt（II） complexes, the molecules have the best conjugation effect and the best TPA properties.

The rates of protein folding with photon absorption or emission and the cross section of photon -protein inelastic scattering are calculated from quantum folding theory by use of a field-theoretical method. All protein photo-folding processes are compared with common protein folding without the interaction of photons （non-radiative folding）. It is demonstrated that there exists a common factor （thermo-averaged overlap integral of the vibration wave function, TAOI） for protein folding and protein pho- to-folding. Based on this finding it is predicted that （i） the stimulated photo-folding rates and the photon-protein resonance Raman scattering sections show the same temperature dependence as protein folding; （ii） the spectral line of the electronic transition is broadened to a band that includes an abundant vibration spectrum without and with conformational transitions, and the width of each vibration spectral line is largely reduced. The particular form of the folding rate--temperature relation and the abundant spectral structure imply the existence of quantum tunneling between protein conformations in folding and pho- to-folding that demonstrates the quantum nature of the motion of the conformational-electronic system.