•Carrier mobilities in n-type compensated silicon are measured.•The origin of discrepancy between Klaassen’s model and measured result is critically discussed.•An optimized model of carrier mobility is proposed for the compensated silicon.•Evolution of resistivity of the n-type compensated Cz silicon is investigated.•Evolution of hole mobility of the n-type compensated Cz silicon is studied.Research on electrical properties of the compensated silicon is very crucial for understanding the doping layer and compensated substrates of solar cells. Regarding the fact that there are still inadequate experimental data of carrier mobility on the n-type compensated silicon, hence in this paper, both majority electron and minority hole mobilities measured on the n-type compensated solar-grade silicon substrates are presented. Prediction models of carrier mobility are essential for material characterization and device (e.g. solar cells) simulation. However, as prediction models of carrier mobility are commonly established based on the uncompensated silicon, large deviations of carrier mobility have been observed on the compensated silicon. In this work, the standard Klaassen’s model and optimized model for the compensated silicon by Schindler et al. are reviewed and compared to measured carrier mobilities. Moreover, the factors that lead to deviations of Klaassen’s model on the n-type compensated silicon are critically discussed, and then we propose an optimized model for prediction of carrier mobility in the compensated silicon. This model can also be extended to both majority and minority carrier mobilities in p- and n-type compensated silicon and fits well with previous published data as well as carrier mobility data presented here. In addition, evolutions of majority electron and minority hole mobilities as crystal grows are also simulated for n-type compensated Czochralski silicon which agrees well with our measured results.

Polyaniline (PANI) and carbon nanotubes (CNTs) are introduced into activated carbon fiber felt (ACFF) to fabricate ACFF/PANI/CNT composite textiles as free-standing and flexible electrodes of supercapacitors. ACFF is an electrochemically active substrate with an electric double-layer capacitance of 2442 mF/cm2, and deposited PANI further offers a large pseudocapacitance. Meanwhile, CNTs optimize the electrical property of the ACFF/PANI/CNT textiles. Consequently, areal capacitance, energy density and power density of the composite textiles are as large as 5611 mF/cm2, 185 μWh/cm2 and 4517 μW/cm2, respectively, much higher than those of many previously reported flexible supercapacitor electrodes. Besides, the textiles display good rate capability, cycling stability and mechanical flexibility. Overall, our flexible textile electrodes are promising to be utilized to power wearable electronics.

•The electronic structures of Ca5(PO4)3Cl host were calculated via DFT.•Temperature-dependent PL property of Ca5(PO4)3Cl:Eu2+ was studied.•Quantum efficiency behaviors of the samples were investigated.•Ra of 96.65 at a warm CCT of 3902 K was obtained for fabricated WLEDs.A blue-emitting Ca5(PO4)3Cl:Eu2+ phosphor was prepared via a conventional high temperature solid-state reaction method. Crystal and electronic structure properties of the Ca5(PO4)3Cl:Eu2+ phosphor were investigated using X-ray diffraction and density functional theory (DFT), respectively. The micro-morphology, reflectance spectra, thermal stability and quantum efficiency of the Ca5(PO4)3Cl:Eu2+ phosphor were also studied. The optimum Eu2+ concentration in Ca5(PO4)3Cl was determined to be 2.0 mol% and the concentration quenching mechanism can be explained by the dipole–dipole interaction. The emission intensity of the Ca5(PO4)3Cl:Eu2+ phosphor was 58.2% of the initial value when the measured temperature increased from 30 °C to 150 °C. The activation energy was determined to be 0.254 eV, suggesting the good stability of this phosphor. A bright blue LED was fabricated using an InGaN-based near-UV LED chip (385 nm) and a Ca5(PO4)3Cl:Eu2+ phosphor, and has an excellent blue-emitting property with CIE coordinates of (0.1480, 0.0350). Furthermore, a bright near-UV warm white LED was fabricated using an InGaN-based near-UV LED chip (395 nm) in combination with the present blue phosphor and the commercial green and red phosphors, which exhibits an excellent color-rendering index (Ra = 96.65) at a warm correlated color temperature of 3902 K with CIE coordinates of (0.3781, 0.3879). All the results suggest that the Ca5(PO4)3Cl:Eu2+ phosphor is a potential blue-emitting candidate for the application in the near-UV pumped blue and warm white LEDs.

•A simple method was proposed to fabricate Ni supersaturated Si sample (p-Si:Ni).•The p-Si:Ni was fabricated using continue-wave laser for the first time.•Ni concentration exceeds the Mott limit within a thickness of about 35 nm.•At 300 K, the p-Si:Ni presented a significant sub-bandgap photo-response.We reported our successful fabrication of Ni supersaturated p-type Si sample (p-Si:Ni) through continuous-wave laser scanning of Ni film deposited on p-type monocrystalline Si wafer. To our knowledge, this is the very first report to fabricate a p-Si:Ni, particularly using a linear type continuous-wave laser irradiation technique. Secondary ion mass spectrometry (SIMS) measurement demonstrates that Ni concentration exceeds the theoretical Mott limit within a thickness of about 35 nm. The cross-sectional transmission electron microscopy images reveal that some nanoparticles emerged in the surface layer of the p-Si:Ni, which exhibits a phenomenon of enhanced Raman scattering. More importantly, the room-temperature (RT) optoelectronic response of the p-Si:Ni was characterized by the Surface Photovoltage Spectroscope technique, and the measurement results reveal that the p-Si:Ni shows a significant sub-bandgap optoelectronic response of about 0.15–0.18 V/W in the range of 1200–1750 nm, validating the p-Si:Ni as a promising Si-based material in the field of RT infrared detection.

A series of Eu2+ doped Sr5(PO4)3Cl blue-emitting phosphors was prepared by conventional high-temperature solid-state reactions. The crystal structure, electronic structure, reflectance spectra, thermal stability and quantum efficiency of the Sr5(PO4)3Cl:Eu2+ phosphor, as well as its application in near-UV white light-emitting diodes have been investigated. The optimization of the lattice parameters and the electronic structure of the Sr5(PO4)3Cl host matrix have been calculated based on density functional theory (DFT). The crystal structure of Sr5(PO4)3Cl:Eu2+ was confirmed by X-ray diffraction. The concentration quenching of Eu2+ ions in the Sr5(PO4)3Cl host is determined to be 1.0 mol% and the physical mechanism of concentration quenching can be explained by the dipole–dipole interaction. Through theoretical calculation, the color purity of the as-prepared Sr5(PO4)3Cl:Eu2+ phosphor is found to be much better than the commercial compound, blue-emitting BaMgAl10O7:Eu2+ (BAM:Eu2+). In particular, a near-UV white LED was fabricated by using an InGaN-based near-UV LED chip (395 nm) and a mixture of Sr5(PO4)3Cl:Eu2+, green-emitting (Ba,Sr)2SiO4:Eu2+ and red-emitting CaAlSiN3:Eu2+ phosphors. The obtained LED device exhibits an excellent color-rendering index (Ra = 94.65) at a correlated color temperature of 3567.84 K with CIE coordinates (0.3952, 0.3709). The above results suggest that the Sr5(PO4)3Cl:Eu2+ phosphor is a promising blue-emitting phosphor for application in near-UV white light-emitting diodes.

A novel green-emitting phosphor Tb3+ doped NaBaBO3 was prepared using a conventional high temperature solid-state reaction method. The crystal structure and luminescence properties of NaBaBO3:Tb3+ were studied. The NaBaBO3 host was also investigated using density functional theory calculations. Our calculated lattice parameters of NaBaBO3 host were found to be in excellent agreement with experiment. Theoretically, the host matrix NaBaBO3 was a wide-gap semiconductor with a direct band gap of 3.66 eV, where the bottom of conduction band and the top of valence band were dominated by Ba 5d state and O 2p state, respectively. The excitation spectra indicated that the phosphor could be effectively excited by near ultraviolet light. The phosphor featured a satisfactory green performance with the highest photoluminescence intensity located at 543 nm excited by 377 nm light and the measured Commission Internationale de L'Eclairage (CIE) chromaticity was determined to be (0.2860, 0.4640). The optimum Tb3+ concentration in NaBaBO3 was 5.0 mol.%. The concentration quenching occurred when Tb3+ concentration was beyond 5.0 mol.% and the concentration quenching mechanism could be explained by the dipole-dipole interaction. The effects of charge compensators (including Li+, Na+ and K+) and temperature on the photoluminescence of NaBaBO3:Tb3+ were also studied. The present work suggested that the NaBaBO3:Tb3+ phosphor was a promising green-emitting material for near ultraviolet white light-emitting diodes.Effect of different charge compensators on the emission intensity of NaBaBO3:Tb3+ (Inset: PL emission spectra of the NaBa0.90BO3: 0.05Tb3+,0.05Li+ phosphor excited by 377 nm and a commercial green phosphor (Ba,Sr)2SiO4:Eu2+ excited by 365 nm)

•The electronic properties of the host matrix KMgBO3 were investigated.•The PL properties on rare earth ions doped KMgBO3 phosphors were studied.•The chromaticity properties on rare earth ions doped KMgBO3 samples were studied.•Tm3+ and Eu3+ doped KMgBO3 samples show higher color purity than commercial phosphors.In this work, the optimization of the geometry and the electronic properties of the host matrix KMgBO3 were investigated using density functional theory, and the comprehensive photoluminescence and chromaticity properties on five rare earth ion-doped (RE = Ce3+, Tm3+, Tb3+, Eu3+, Dy3+) KMgBO3 phosphors were also studied. By introducing RE ions into the KMgBO3 host, excellent purple, blue, green, red and white emitting light could be obtained under the near-ultraviolet light excitation. The results suggest that rare earth doped KMgBO3 phosphors are potential luminescence materials for the application in the near-ultraviolet white light-emitting diodes.

Tb3 +-doped Sr2B2O5 green phosphor was synthesized by solid-state reaction method. The structure and luminescence properties of the phosphor were studied. The excitation and emission spectra indicate that this phosphor can be effectively excited by ultraviolet (UV) 376 nm, and exhibit bright green emission centered at 545 nm corresponding to the 5D4 → 7F5 transition of Tb3 +. It is shown that the 7 mol% of doping concentration of Tb3 + ions in Sr2B2O5: Tb3 +, Li+ phosphor is optimum, and the concentration quenching occurs when the Tb3 + concentration is beyond 7 mol%. The concentration quenching mechanism can be interpreted by the quadrupole–quadrupole interaction of Tb3 + ions. The present work suggests that the novel green phosphor is a kind of potential green-emitting phosphor.Highlights► In the paper, Tb3+ -doped Sr2B2O5 phosphor was synthesized by solid-state reaction. ► This phosphor can be effectively excited by ultraviolet (UV) 376 nm. ► It exhibits bright green emission centered at 545 nm (5D4 → 7F5). ► Therefore, the phosphor is a promising green phosphor.

The removal of metal impurities from metallurgical grade silicon (MG-Si) by acid leaching has been investigated with the addition of CaO. Prior to adding CaO, Fe is the main impurity in the MG-Si sample, and the 2nd-phase precipitates in silicon are Si-Fe-based alloys, such as Si-Fe, Si-Fe-Ti, Si-Fe-Al, Si-Fe-Mn, and Si-Fe-Ni. The phases of Si-Fe and Si-Fe-Ti are not appreciably soluble in HCl. After the introduction of CaO, Ca becomes the dominant impurity, and the 2nd-phase precipitates become Si-Fe-based alloys, such as Si-Ca, Si-Ca-(Fe, Ti, Ni, Al), and Si-Ca-Fe-Al. These are effectively leached with HCl. Therefore, the HCl leaching effect on the removal of metal impurities has been improved. The optimum content of Ca in the MG-Si samples after adding CaO is in the range of 1 pct to 4 pct, the contents of Fe, Al, Ti, and Ni have been decreased to a minimum of less than 5 ppmw (ppm by weight) each, and the acid leaching results do not show a dependence on Ca content at this range.

A series of Eu2+ doped Sr5(PO4)3Cl blue-emitting phosphors was prepared by conventional high-temperature solid-state reactions. The crystal structure, electronic structure, reflectance spectra, thermal stability and quantum efficiency of the Sr5(PO4)3Cl:Eu2+ phosphor, as well as its application in near-UV white light-emitting diodes have been investigated. The optimization of the lattice parameters and the electronic structure of the Sr5(PO4)3Cl host matrix have been calculated based on density functional theory (DFT). The crystal structure of Sr5(PO4)3Cl:Eu2+ was confirmed by X-ray diffraction. The concentration quenching of Eu2+ ions in the Sr5(PO4)3Cl host is determined to be 1.0 mol% and the physical mechanism of concentration quenching can be explained by the dipole–dipole interaction. Through theoretical calculation, the color purity of the as-prepared Sr5(PO4)3Cl:Eu2+ phosphor is found to be much better than the commercial compound, blue-emitting BaMgAl10O7:Eu2+ (BAM:Eu2+). In particular, a near-UV white LED was fabricated by using an InGaN-based near-UV LED chip (395 nm) and a mixture of Sr5(PO4)3Cl:Eu2+, green-emitting (Ba,Sr)2SiO4:Eu2+ and red-emitting CaAlSiN3:Eu2+ phosphors. The obtained LED device exhibits an excellent color-rendering index (Ra = 94.65) at a correlated color temperature of 3567.84 K with CIE coordinates (0.3952, 0.3709). The above results suggest that the Sr5(PO4)3Cl:Eu2+ phosphor is a promising blue-emitting phosphor for application in near-UV white light-emitting diodes.