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The operation of dye-sensitized solar cells and quantum dot-sensitized solar cells (QDSSCs) depends strongly on the photoanode material employed. This is addressed in the present work by developing photoanodes based on a double-layer TiO2 inverse opal material with different interconnected pore sizes in the bottom and upper layers for use in QDSSCs. The proposed photoanode material leads to better infiltration of the sensitizers and the hole transporting material through the entire depth of the TiO2 layer. Double-layer TiO2 inverse opal-based QDSSCs are demonstrated to facilitate the greater absorbance of quantum dots and obtain higher photocurrent and power conversion efficiency than QDSSCs adopting single-layer TiO2 inverse opal photoanodes. Various QDSSCs employing double-layer TiO2 inverse opal photoanodes with different pore sizes in the layers are tested. The CdS/CdSe co-sensitized solar cell adopting the optimum photoanode configuration and thickness provided the highest QDSSC conversion efficiency of 5.79%.

The beams with phase gradients along the line trajectory, i.e., with the momentum flux transverse to the optical axis were generated with the beam shaping method and applied for optical manipulations in this paper. The phase distributions of the reconstructed beam in the focal plane of the objective and the moving velocity of the trapped microparticles were experimentally investigated. The experimental results showed that the moving velocity of the trapped microparticles is linearly dependent on the phase gradient possessed by the reconstructed beam. Furthermore, a generated curve beam was used to transport microparticles quickly and automatically along the curved route to avoid an obstacle. The generation method of the beams with phase gradients is simple. The beams would have potential applications in the fields such as optical trapping and optical sorting.

The Tm3+/Ho3+-SrLaGa3O7 crystal was grown using the Czochralski (CZ) method. The absorption spectra, the fluorescence spectra around 2.0 μm and energy-transfer (ET) schemes between Tm3+ ions and Ho3+ ions has been studied. The lasing performance of Tm3+/Ho3+-SrLaGa3O7 crystal for a-cut and c-cut pumped by a fiber-coupled laser diode laser are presented in this paper. The maximum output powers of 6.15 W for a-cut crystal at 2041 nm and 2.51 W for c-cut crystal at 2044 nm have been obtained, respectively. The maximum slope efficiency in terms of absorbed pump power nearly reached 36.5% for the a-cut crystal and about 18.8% for the c-cut crystal. In addition, the width of tuning can reach about 450 nm, suggesting the potential of these crystals for ultrashort pulse generation by mode-locking.

Yb3+ doped BaLaGa3O7 crystal has been successfully grown by Czochralski method. The polarized absorption spectra, the fluorescence spectra and the fluorescence decay lifetime of Yb3+:BaLaGa3O7 crystal were measured at room temperature. The spectroscopic parameters of Yb3+:BaLaGa3O7 crystal are calculated. A continuous wave output power of 1.32W was obtained with four-wavelength emission corresponding to an optical-optical slope efficiency of 55%.

Intra-cavity third harmonic generation was investigated comparatively in both single- and multi-pass operations from a side-pumped acousto-optic Q-switched Nd:YAG laser. Under the pump current of 19 A, 1.68 W and 2.2 W output power at 355 nm were obtained at 9.5 kHz in single and multi-pass THG operation respectively, with a power ratio of 76%. It clarified that the first THG process in multi-pass operation played a key role in the whole frequency-tripling process. The result provided the issue that efficient third harmonic laser could be achieved via optimizing the intra-cavity single-pass THG operation due to its high beam quality.

A multi-primary color display, such as the six-primary color format, is a solution in expanding the color gamut of a full-color flat panel display. The performance of a multi-primary color display based on organic/polymer light-emitting diodes was analyzed in this study using the fitting curves of the characteristics of devices (i.e., current density, voltage, luminance). A white emitter was introduced into a six-primary color format to form a seven-primary color format that contributes to energy saving, and the ratio of power efficiency of a seven-primary color display to that of a six-primary color display would increase from 1.027 to 1.061 by using emitting diodes with different electroluminescent efficiencies. Different color matching schemes of the seven-primary color format display were compared in a uniform color space, and the scheme of the color reproduction did not significantly affect the display performance. Although seven- and six-primary color format displays benefit a full-color display with higher quality, they are less efficient than three-primary (i.e., red (R), green (G), and blue (B), RGB) and four-primary (i.e., RGB+white, RGBW) color format displays. For the seven-primary color formats considered in this study, the advantages of white-primary-added display with efficiently developed light-emitting devices were more evident than the format without a white primary.

We demonstrate for the first time, to our certain knowledge, a dual-wavelength passively Q-switched bulk laser based on the MoS2/graphene heterojunction saturable absorber. This heterojunction is prepared though a facile hydrothermal reaction and shows an excellent saturable absorption charateristic with the modulation depth of 9.12%. A 370 ns pulse laser with single pulse energy of 0.734 μJ is achieved. The corresponding output power and repetition frequency rate are 102 mW and 138.9 kHz, respectively. The stable pulse laser operates at 1047.2 and 1049.6 nm, simultaneously. This work validates the MoS2/graphene heterojunction is a promising saturable absorber for multiwavelength near-infrared pulse lasers and it may broaden the range to choose optical modulator.

A modified helical phase is presented in this paper. The generated vortex beams with the modified helical phases are characterized with ring-broken intensity distributions. The transverse intensity patterns of the generated vortex beams at a defined axial position and the focal plane are analyzed, respectively. The results demonstrate that the generated beam has an opening, whose size can be customized with a variable l′. The proposed vortex beams realized optical guiding of microparticles in the transverse planes of the beams. This kind of ring-broken beams will be promising for optical manipulation. Keywords: Helical phase, Optical vortices, Optical manipulation

The good catalytic activity, resistance to iodine corrosion, and stability of carbon materials make them ideally suited for the fabrication of counter electrodes used in dye-sensitized solar cells (DSSCs). Different carbon materials have been used to make counter electrodes, and each has its own advantages, such as good film formation or high electric conductivity. Herein, various carbon materials were mixed and employed for preparing counter electrodes in DSSCs. Both fine film morphology and improved charge-carrier transport were obtained, and the power conversion efficiency of the DSSCs was thus increased. Accordingly, a cell efficiency of 6.29% was obtained by the DSSC with a counter electrode composed of the optimum mixture of carbon nanotubes, graphite, conductive carbon black, and graphene. Furthermore, DSSCs with a flexible counter electrode were fabricated using the optimum carbon material mixture, and the corresponding DSSCs achieved a power conversion efficiency of 4.32%.

A 2.07 at.% Sm3+-doped CaYAlO4 crystal was grown by the Czochralski method. The polarized spectra and decay curve were recorded at room temperature. The spectroscopic parameters were calculated on the basis of Judd-Ofelt theory. The absorption cross-sections at 408 nm were obtained to be 2.43 × 10−20cm2 and 4.09 × 10−20cm2 for the π and σ polarization, respectively. The main emission band, which had a fluorescence branching ratio of 45.51%, was located at 601 nm with cross-sections of 10.06 × 10−22 cm2 (π-polarization), 6.97 × 10−22 cm2 (σ-polarization). The decay lifetime of 4G5/2 multiplet was measured to be 0.83 ms. The Sm3+:CaYAlO4 crystal also has a good temperature-dependent fluorescence property. The results indicate the Sm3+:CaYAlO4 crystal may be a potential candidate of orange-yellow laser pumped directly by the GaN/InGaN laser diode.

The electronic and optical properties before and after Au decoration on (1 0 1 ¯ 4) surface of dolomite were investigated based on first principles calculations. The electronic structure analysis indicates that the band gap decreases from 4.25 eV (pristine) to 0.81 eV (1 Au decorated case), and the work functions increase from 2.41 eV to 3.53 eV. The density of states analysis revealed that the band gap decrease is mainly attributed to the Au 5d doping states in the forbidden band gap. Moreover, an additional peak located at 310 nm of polarization direction on E//c appears after Au decoration, resulting in the increased absorption intensity in the ultraviolet and visible range. By comparing the redox potential with that of different kinds of pollution gas, it can be found that the Au decorated dolomite might be a good photocatalyst for NO removal. The above results indicate that the Au decorated dolomite could be used in visible light photocatalysis or photovoltaic applications due to its semiconductor characteristics and suitable redox potentials.

We report a 2 micron passively Q-switched bulk state pulsed laser with a pulse of 430 ns based on graphene-like 2D WS2 nanosheets. To the best of our knowledge, it is the shortest pulse compared with other bulk state lasers based on WS2 saturable absorbers at this waveband. The WS2 nanosheets are prepared through a facile hydrothermal reaction. Its max output power and pulse energy are 488 mW and 5.422 μJ, respectively. The wavelength is distributed from 1934 to 1942 nm. These results reveal that WS2 is a promising nanomaterial in the fields of photonics and electronics.

Tm 3+ -, Dy 3+ -BaLaGa 3 O 7 phosphors have been synthesized by solid-phase sintering. X-ray diffraction (XRD) and photoluminescence properties of the phosphors were investigated in detail. The sample Tm 3+ and Dy 3+ ions co-doped BaLaGa 3 O 7 obtain white light emission by integrating a blue emission band located at 455 nm ( 1 D 2 → 3 F 4 ) and an orange one located at 573 nm ( 4 F 9/2 → 6 H 13/2 ) attributed to Tm 3+ and Dy 3+ ions, respectively. The study on the luminescence mechanism showed that there is the energy transfer between Tm 3+ and Dy 3+ in Tm 3+ /Dy 3+ -BaLaGa 3 O 7 phosphors.

Quantitative structure–activity relationship (QSAR) studies were performed in this work to predict the pIC50 of non-glycoside sodium-dependent glucose cotransporter-2 (SGLT2) inhibitors (46 triazole derivatives). Four descriptors were selected from the pool of DRAGON descriptors using the enhanced replacement method. Three nonlinear regression methods—multilayer perceptron neural network (MLP NN), support vector machine (SVM), and projection pursuit regression (PPR)—were then used to build the QSAR models. The performance of the obtained models was assessed through the cross-validation and external validation of the test set. PPR produced a better model than MLP NN and SVM with coefficients of determination of 0.962 and 0.871 and root mean square errors of 0.162 and 0.471 for the training and test sets, respectively. This study developed simple and efficient approaches to predict the pIC50 of triazole derivatives and provided some insights into their structural features for the development of more potential SGLT2 inhibitors.

In this letter, we describe the operation of an end-pumped acousto-optic Q-switched Nd:YLF laser. According to the theoretical analysis and calculation for Nd:YLF crystal, the thermal focal length of σ-polarized laser is positive in plane-parallel resonator, while that of π-polarized laser is negative. Hence laser operation at σ-polarized 1313 nm should be stable in plane-parallel cavity. When absorbed pump power is 12.45 W and the pulse repetition frequency is 10 kHz, 3.1 W output laser at 1313 nm is achieved. As a result, the optical–optical conversion efficiency is 25.4 % and slope efficiency is 31.2 %, respectively.

We demonstrate a diode-end-pumped continuous laser operating a new wavelength at 1370 nm in Nd: YLF. It is a coherent radiation exactly lies in the absorption band of the C 70 and water vapor. A maximum output power up to 4 W is achieved at an incident pump power of 14.6 W, with a slope efficiency of 35.5%, and the optical-optical efficiency of 27.4%. The laser output power instability in half an hour is less than 3%. Calculated by experimental threshold data, the stimulated emission cross section of 1370 nm transition in Nd: YLF crystal is determined to be 0.4437×10 −20 cm 2 .

High-quality single crystals of different Er3+ concentration doped SrGdGa3O7(SGGO) were grown successfully by the Czochralski method. The absorption, up-conversion, near-infrared and mid-infrared fluorescence spectra, as well as the fluorescence decay curves of Er:4I13/2 and 4I11/2 levels in Er:SGGO crystal were measured at room temperature. As the concentration of Er3+ ions increase, the spectra of Er:SGGO crystals show weaker near-infrared emission and stronger mid-infrared emission. The lifetime of the 4I13/2 state decreases by nearly 7times while the lifetime of the 4I11/2 state decreases by only about 1.3 times in the Er:SGGO crystals. These results indicate that the heavily Er3+ doped SGGO crystals is beneficial to improve the 2.7 μm laser.

The stability and electronic structures of fluorinated Janus MoSSe (MoSSe-Fx, x = 0–16) were investigated by the first-principles method. Energetically, the Setop site of Janus MoSSe is the most favorable site for F-adsorption. Based on the adsorption, binding and formation energy analysis, it seems the fluorinated Janus MoSSe is stable. The analysis of the electronic density distribution and orbital hybrid shows that the fluorinated Janus MoSSe forms stable structure as well. Then, the electronic structure and work function change with the concentration of F atoms analyzed. With the increase of adsorbed F atoms, the bandgap of Janus MoSSe-Fx decreases from 1.456 (pristine case, [Formula: see text]) to 1.073[Formula: see text]eV (semi-fluorinated case, [Formula: see text]), and changes from direct to indirect bandgap semiconductor. It is noteworthy that there are some additional doping levels near the valence band after F adsorbed, which originated from the F 2[Formula: see text] doping states. The charge population analysis shows that electrons transfer was from Se to F atoms. It is worth noting that the charge on F atom (MoSSe-F16) is two times more than Se atoms in pristine Janus MoSSe (MoSSe-F0). As a result, the built-in electric field pointed from Mo to F atoms is enhanced, resulting in the tremendous increase of the work function for fluorinated Janus MoSSe. The work function changes from 5.22[Formula: see text]eV ([Formula: see text]) in pristine case to 8.30[Formula: see text]eV after semi-fluorinated ([Formula: see text]). Therefore, due to the adjustable work function and built-in electric field, the fluorinated Janus MoSSe monolayer shows better properties for applications in the piezoelectric device, optoelectronic device or photocatalyst.

Quantitative structure–property relationship modelling can be a valuable alternative method to replace or reduce experimental testing. In particular, some endpoints such as octanol–water (KOW) and organic carbon–water (KOC) partition coefficients of polychlorinated biphenyls (PCBs) are easier to predict and various models have been already developed. In this paper, two different methods, which are multiple linear regression based on the descriptors generated using Dragon software and hologram quantitative structure–activity relationships, were employed to predict suspended particulate matter (SPM) derived log KOC and generator column, shake flask and slow stirring method derived log KOW values of 209 PCBs. The predictive ability of the derived models was validated using a test set. The performances of all these models were compared with EPI Suite™ software. The results indicated that the proposed models were robust and satisfactory, and could provide feasible and promising tools for the rapid assessment of the SPM derived log KOC and generator column, shake flask and slow stirring method derived log KOW values of PCBs.