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To improve the efficiency of polycrystalline silicon solar cells, process optimization is a key technology in the photovoltaic industry. Despite the efficiency of this technique to be reproducible, economic, and simple, it presents a major inconvenience to have a heavily doped region near the surface which induces a high minority carrier recombination. To limit this effect, an optimization of diffused phosphorous profiles is required. A "low-high-low" temperature step of the POCl3 diffusion process was developed to improve the efficiency of industrial-type polycrystalline silicon solar cells. The low surface concentration of phosphorus doping of 4.54 × 1020 atoms/cm3 and junction depth of 0.31 μm at a dopant concentration of N = 1017 atoms/cm3 were obtained. The open-circuit voltage and fill factor of solar cells increased up to 1 mV and 0.30%, compared with the online low-temperature diffusion process, respectively. The efficiency of solar cells and the power of PV cells were increased by 0.1% and 1 W, respectively. This POCl3 diffusion process effectively improved the overall efficiency of industrial-type polycrystalline silicon solar cells in this solar field. [ABSTRACT FROM AUTHOR]

Here, we demonstrate the broadband spectra and efficient laser performance of a disordered Nd:Sr0.7La0.3Mg0.3Al11.7O19 (Nd:ASL) crystal. The polarized absorption and emission spectra were characterized and calculated with the Judd–Ofelt (J–O) theory, and the results show that this crystal has relatively large σ polarized absorption and emission cross sections, with peak emission cross sections of 4.5 × 10−20 cm2 at 1051 nm and an emission width of 30 nm at 1074 nm, which are favorable for pulsed lasers. The laser-diode-pumped continuous-wave (CW) and passively Q-switched lasers at 1051 nm were realized for the first time to our best knowledge. For CW laser, the maximum output power was 1.95 W with the slope efficiency of 42.6%, and for the passive Q-switching, the maximum output power was 0.73 W with the pulse width of 7.96 ns and peak power of 5.64 W. The results demonstrate that Nd:ASL crystal is a potential candidate for lasers, especially high-peak pulsed lasers such as Q-switching and mode-locking. [ABSTRACT FROM AUTHOR]

This work reports the modification of egg shell (ES) particles by using stearic acid (SA) and their reinforcement in the epoxy matrix. The ES treatment via SA was optimized, the optimum conditions for concentration, temperature, and time were found to be 2.5%, 85 °C, and 50 min, respectively. The untreated ES (UES) and treated ES (TES) particles were characterized by Fourier transform infrared spectroscopy (FTIR), differential scanning calorimetry (DSC), X-ray diffraction (XRD), scanning electron microscope (SEM), particle size distribution, and contact angle. FTIR confirmed the chemical modification of SA on ES surface and DSC reflects an endothermic peak at 240 °C. XRD reveal a decrease in crystal size and crystallinity, while contact angle increases to 169° from 42°. The SEM observations clearly reflect a distinct decrease and separation of small domains of ES particles thus improving an increased surface area. Afterwards, the UES and TES particles were reinforced in epoxy at 15 and 20 weight (wt.) % loading. The tensile tests confirmed a 22% increase in elongation as compared to pure epoxy due to the hydrogen bonding between TES particles and matrix. The lowest brittleness was recorded for TES/epoxy composites on 20 wt % loading. The TGA confirmed the improved thermal stabilities at 20 wt % loading of TES particles in matrix, the improvements in T5%, T10%, and T20% values were recorded as 33, 26, and 21 °C higher than the corresponding values for neat matrix. The TES/epoxy composites on 20 wt % showed 41% increase in storage modulus as compared to the pristine epoxy, and cross-link density reaches to 2.71 × 10−3 from 1.29 × 10−3 mol/cm3 for neat matrix. The decline in tan δ height and improvement in Tg were also observed. The best adhesion effectiveness was recorded for TES/epoxy composites. This simple and economical modification technique can enhance the application of ES particles in various polymeric coating and composites applications. [ABSTRACT FROM AUTHOR]

In this paper, we report the fabrication of high-quality 5 at. % Er3+ ions doped SrF2 transparent ceramics, the potential candidate materials for a mid-infrared laser-gain medium by hot-pressing at 700 °C for 40 h using a chemically-derived powder. The phase structure, densification, and microstructure evolution of the Er:SrF2 ceramics were systematically investigated. In addition, the grain growth kinetic mechanism of Er:SrF2 was clarified. The results showed lattice diffusion to be the grain growth mechanism in the Er:SrF2 transparent ceramic of which highest in-line transmittance reached 92% at 2000 nm, i.e., very close to the theoretical transmittance value of SrF2 single crystal. Furthermore, the emission spectra showed that the strongest emission band was located at 2735 nm. This means that it is possible to achieve a laser output of approximately 2.7 μm in the 5 at. % Er3+ ions doped SrF2 transparent ceramics. [ABSTRACT FROM AUTHOR]