In this work, we report a lead-free MASnI3 perovskite photodetectors prepared by inverse temperature crystallization method. The surfaces of MASnI3 perovskite films are smooth and evenness. The MASnI3 perovskite photodetectors t has the highest photocurrent value in green light region among the five monochromatic light sources with a photocurrent of 1 uA at bias of 10 V. The advantage of this work is that the manufacturing process is relatively simple and safety, so it can be easily manufactured.
In this experiment, the molybdate phosphors were manufactured by using the solid state amorphization with europium, yttrium and molybdenum. To investigate EuxYy(MoO4)3 phosphor characteristics, the europium and yttrium were blended to different of mole ratio. The europium composition can improve phosphors luminous intensity. Phosphors characteristics was measured by X-ray diffraction, SEM and photoluminescence. The X-ray diffraction and SEM displayed phosphors crystal structure. The photoluminescence of molybdate phosphors show that the best excitation spectra emitting position was at 614nm. The molybdate phosphors was excited by UV laser. Therefore, this molybdate phosphors was suitable for UV-LED.
This work reports the optoelectronic characteristics of the graphene/MAPbI3/TiO2/Si heterostructure and graphene/Pb2/porous Si heterostructure for light-emitting devices with low cost. The XRD diagrams of these two heterostructures show three main peaks at the position of 14.1°, 28.4°, and 31.9°, which correlate with (110), (220), and (310) planes of the MAPbI3 perovskite phase. The PL spectra of these two heterostructures demonstrated three peaks located at 382, 566, and 766 nm. They are corresponding to the emission of B-B transition of TiO2, defects in the TiO2, and B-B transition of MAPbI3. One peak of the EL spectrum of the graphene/MAPbI3/TiO2/porous Si heterostructure operated under the injection current of 10 mA located at around 800 nm was observed.
This work proposes a novel white light device consisted of a yttrium aluminum garnet (YAG) phosphor-doped zinc oxide (ZnO) (ZnO:YAG) thin film deposited on a indium tin oxide (ITO) glass substrate by ultrasonic spray pyrolysis. Characteristics of the ZnO:YAG (YAG at 1, 5, and 10 wt%) film on ITO glass substrates were examined by x-ray diffraction (XRD) pattern, hall measurement, and photoluminescence (PL) pattern spectra. The color of the PL spectra of the yttrium-aluminum garnet (YAG) phosphor-doped zinc oxide (ZnO) thin films under excitation of He-Cd laser with wavelength of 325 nm is nearly white.
This study presents a GaN thin film light-emitting diode (TF-LED) on an electroplated flexible copper substrate to improve thermal conduction effect of the LED. The optoelectronic characteristics and stress effect of the GaN TF-LEDs on the electroplated flexible copper prepared by laser lift-off technique was examined. The surface of the peeled GaN TF-LED after laser lift-off process demonstrated a pore array. The GaN pore array surface was etched by photo-electrochemical method to form hexagonal pyramid hillocks on the surface using KOH solution. Then, freestanding peeled GaN TF-LEDs with the front surface protected by wax were immersed into 3M KOH solution at 10, 20, 30min under ultraviolet illuminations to perform the photo-electrochemical etching. Surface morphologies with and without photo-electrochemical etching were observed by field emission scanning electron microscope (FESEM) (LEO 1530).
We presents graphene-based reflective electrode on Ag films as a reflectively conductive layer for flip-chip GaN-based LEDs to improve optoelectronic characteristics of LEDs. The Ag/graphene films demonstrate thickness of about 200 nm and surface roughness. As annealing at temperature increases from 500°C to 800°C, the location of peak increases from 22.5° to 26.2° with the peak intensity becomes stronger. This may be attributed to the reduction of oxygen functional group. A graphene has first and second Raman-active modes at D band (1350 cm-1) and G band (1592 cm-1), respectively. Optimal conditions for graphene/Ag films contact of the sheet resistance is the smallest value by after heat treatment at temperatures of 800 °C. Further, graphene/Ag films were also applied to GaN-based light-emitting diodes to form an electrode with a p-type ohmic contact.
We presents a nanorods AlN films on sapphire substrate deposited at oblique-angle by a radio-frequency reactive
magnetron sputtering. A nanorods AlN layer was employed as a buffer layer for a GaN-based LEDs to improve
optoelectronic characteristics of LEDs. The diameter of the nanorods AlN buffer layer is in the range of 30-50 nm.
Typical current-voltage characteristics of the GaN-based LEDs with a nanorods AlN buffer layer have a forward-bias
voltage of 3.1 V at an injection current of 20 mA. The output intensity of LEDs initially increases linearly as the
injection current increases from 10 mA to 150 mA. The light output power of the GaN-based LED with a nanoporous
AlN layer was about 31% higher than that of a GaN-based LED without a nanoporous AlN layer at an injection current
of 250 mA.
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