Mn^(4+) activated phosphors in photoelectric and energy conversion devices

Owing to their high luminous efficiency and tunable emission in both red light and far-red light regions,Mn^(4+)ion-activated phosphors have appealed significant interest in photoelectric and energy conversion devices such as white light emitting diode(W-LED),plant cultivation LED,and temperature thermometer.Up to now,Mn^(4+)has been widely introduced into the lattices of various inorganic hosts for brightly redemitting phosphors.However,how to correlate the structure-activity relationship between host framework,luminescence property,and photoelectric device is urgently demanded.In this review,we thoroughly summarize the recent advances of Mn^(4+)doped phosphors.Meanwhile,several strategies like co-doping and defect passivation for improving Mn^(4+)emission are also discussed.Most importantly,the relationship between the protocols for tailoring the structures of Mn^(4+)doped phosphors,increased luminescence performance,and the targeted devices with efficient photoelectric and energy conversion efficiency is deeply correlated.Finally,the challenges and perspectives of Mn^(4+)doped phosphors for practical applications are anticipated.We cordially anticipate that this review can deliver a deep comprehension of not only Mn^(4+)luminescence mechanism but also the crystal structure tailoring strategy of phosphors,so as to spur innovative thoughts in designing advanced phosphors and deepening the applications.

Bi^(3+)-activated dual-wavelength emitting phosphors toward effective optical thermometry

Optical thermometry as an important local temperature-sensing technique,has received increasing attention in scientific and industrial areas.However,it is still a big challenge to develop luminescent materials with self-activated dual-wavelength emissions toward high-sensitivity optical thermometers.Herein,a novel ratiometric thermometric strategy of Bi^(3+)-activated dual-wavelength emission band was realized in the same lattice position with two local electronic states of La_(3)Sb_(1-x)Ta_xO_(7):Bi^(3+)(0≤x≤1.0)materials based on the different temperature-dependent emission behaviors,benefiting from the highlysensitive and regulable emission to the coordination environment of Bi^(3+).The structural and spectral results demonstrate that the emission tremendously shifted from green to blue with 68 nm and the intensity was enhanced 2.6 times.Especially,the visual dual-wavelength emitting from two emission centers was presented by increasing the Ta^(5+)substitution concentration to 20%or 25%,mainly originating from the two local electronic states around the Bi^(3+)emission center.Significantly,the dual-wavelength with different thermal-quenching performance provided high-temperature sensitivity and good discrimination signals for optical thermometry in the range between 303 and 493 K.The maximum relative sensitivity reached 2.64%/K(La_(3)Sb_(0.8)Ta_(0.2)O_(7):0.04Bi^(3+)@383 K)and 1.91%/K(La_(3)Sb_(0.75)Ta_(0.25)O_(7):0.04Bi^(3+)@388 K).This work reveals a rational design strategy of different local electronic states around the singledoping multiple emission centers towards practical applications,such as luminescence thermometry and white LED lighting.

Biomolecule-assisted Solvothermal Synthesis of Bismuth Sulfide Nanorods

A simple biomolecule-assisted synthetic route has been successfully developed to prepare bismuth sulfide（Bi 2 S 3 ） nanorods under solvothermal conditions.In the synthetic system,pentahydrate bismuth nitrate was employed to supply Bi source and L-cystine was used as sulfide source and complexing agent.The morphology,structure,and phase composition of the as-prepared Bi 2 S 3 products were characterized by X-ray diffraction（XRD）,energy dispersion spectroscopy（EDS）,X-ray photoelectron spectroscopy（XPS）,field-emission scanning electron microscopy（FESEM）,transmission electron microscopy（TEM）,selected area electron diffraction（SAED）,and high-resolution transmission electron microscopy（HRTEM）.The experimental results show that the nanorods have uniform diameter of 100-200 nm and length of 2-4 μm.The possible formation mechanism for the bismuth sulfide nanorods was discussed.

Preparation and Characterization of Flower-like Cu_2SnS_3 Nanostructures by Solvothermal Route

Flower-like Cu2SnS3 nanostructures composed of nano-flakes were successfully synthesized by solvothermal technique at 180 ℃ for 16 h. In the preparation process, CuCl2·H2O, SnCl2·2H2O and thiourea were used as raw materials, and ethylene glycol were used as solvent. The results showed that the obtained product was pure phase Cu2SnS3. The average diameter of Cu2SnS3 flowers and the thickness of the nano-flakes were about 1-1.5 μm and 10 nm, respectively. The influence of reaction time and solvents on the morphology, size and structure of the products was investigated by powder X-ray diffraction and field-emission scan electron microscopy （FESEM）. The ultraviolet-visible absorption spectrum measurement indicated that the band gap of the sample was about 1.26 eV and could be applied to the absorbing layer of thin solar cell. The possible formation mechanism of flower-like Cu2SnS3 was also proposed and discussed.