Thermal dissipation had an important influence in the quantum effect and life of light emitting diodes (LED) because it enabled heat transfer away from electric devices to the aluminum plate for heat removal. In the industrial processing, the quality of the thermal dissipation was decided by the gumming technique between the PCB and aluminum plate. In this study, we made the ceramic thin films of diamond like carbon (DLC) by vacuum sputtering between the substrate and high power light emitting diodes (HPLED) light to check the influence of heat transfer by DLC thin films. The ceramic dielectric coatings were characterized by several subsequent analyses, especially the measurement of real work temperature of HPLEDs. The X-Ray photoelectron spectroscopy (XPS) patterns revealed that ceramic phases were successfully grown onto the substrate. At the same time, the real work temperatures showed the thickness of DLC thin film coating effectively affected the thermal conduction of HPLEDs.
Thermal dissipation had an important influence in the effect and life of light emitting diodes (LED) because it enables transfer the heat away from electric device to the aluminum plate that can be used for heat removal. In the industrial processing, the quality of the thermal dissipation decides by the gumming technique between the PCB and aluminum plate. In this study, we fabricated double layer ceramic thin films of diamond like carbon (DLC) and alumina nitride (AlN) by vacuum sputtering soldered the substrate of high power light emitting diodes (HPLED) light to check the heat conduction. The ceramic dielectric coatings were characterized by several subsequent analyses, especially the measurement of real work temperature. The X-Ray photoelectron spectroscopy (XPS) patterns reveal those ceramic phases were successfully grown onto the substrate. The work temperatures show DLC and AlN films coating had limited the heat transfer by the lower thermal conductivity of these ceramic films. Obviously, it hadn’t transferred heat and limited work temperature of HPLED better than DLC thin film only.
Thermal dissipation had an important influence in the quantum effect of light emitting diodes (LED)
because it enables transfer the heat from electric device away from the heat to the aluminum plate that
can be used for heat removal. In the industrial processing, the quality of the thermal dissipation decides
by the gumming technique between the PCB and aluminum plate. In this study, we fabricated a
ceramic thin film of diamond like carbon (DLC) by vacuum sputtering, soldered the substrate of LED
light to enhance the heat transfer. The dielectric coatings were characterized by several subsequent
analyses, especially the measurement of real temperature. The X-Ray diffraction (XRD) diagram
analysis reveals those ceramic phases were successfully grown on the individual substrate. The results
show DLC thin film coating fabricated by vacuum sputtering has lower sheet resistivity, higher
hardness, critical load, and thermal conduction, 3.5 Wm-1 K-1 to the purpose. The real temperature
showed DLC thin film couldn’t transfer heat enough and limited work temperature of LED
successfully as compared to aluminum nitride.
This study primarily employed poly-(3-hexylthiophene) (P3HT): [6,6]-phenyl C61-butyric acid methyl
ester (PC61BM) solvent to produce single-layer organic photovoltaic (OPV) cell of single-layer bulk
heterojunction (BHJ). The OPV cell structure is ITO/PEDOT:PSS/P3HT:PC61BM/LiF/Al. In the
process, we examined the optoelectronic properties of producing P3HT:PC61BM single-layer OPV cells
in various thicknesses of active layer, temperatures, and times of thermal pre- and post-annealing. The
results showed that the maximum conversion efficiency (ηp) of single-layer OPV cells increased in
crystal level of P3HT molecule from low temperature to high temperature process and effective contact
area between active layer and metal cathode of device. Thus the ηp value of cells can reach 4.58% after
pre- and post-annealing.
The fully conjugated poly[2,6-(4,4-bis(2-ethylhexyl)-4H-cyclopenta [2,1-b;3,4-b′]
dithiophene)-alt-4,7-(2,1,3-benzothiadiazole)] (PCPDTBT) was a low energy gap (Eg) organic polymer
material with polydispersity index (PDI) 1.3. It’s the highest occupied molecular orbital (HOMO) 5.2
eV, the lowest unoccupied molecular orbital (LUMO) 3.75 eV and Eg 1.45 eV. As compared with
poly-(3-hexylthiophene) (P3HT), the lower Eg made the more absorption in the near-infrared (NIR)
area. Its maximum absorption peak (λmax) was near 800 nm. The optimal conversion efficiency (ηp) of
single-layered PCPDTBT:PC61BM organic photovoltaic (OPV) device reached 2.44% when the
weight ratio of PCPDTBT:PC61BM was 1:2.5. In this study, we changed weight ratio, layer thickness,
and solvent to enhance the optoelectronic properties of OPV devices. Variations the layer thickness
were processed and investigated leading to an optimum ηp of 2.62 % for a single layer OPV cell with
layer thickness of 150nm. The PCPDTBT molecule packed more order when the solvent evaporated to
go slow. However, it did not increase the crystal level of PCPDTBT molecule for enhanced ηp.
Thermal management had an important influence not only in the life time but also in the efficiency of
high power light emitting diodes (HPLEDs). 30 watts in a single package have become standard to the
industrial fabricating of HPLEDs. In this study, we fabricated both of the AlN porous films, by vacuum
sputtering, soldered onto the HPLEDs lamp to enhance both of the heat transfer and heat dissipation. In
our model, the ceramic enables transfer the heat from electric device to the aluminum plate quickly and
the porous increase the quality of the thermal dissipation between the PCB and aluminum plate, as
compared to the industrial processing. The ceramic films were characterized by several subsequent
analyses, especially the measurement of real work temperature. The X-Ray diffraction (XRD) diagram
analysis reveals those ceramic phases were successfully grown onto the individual substrates. The
morphology of ceramic films was investigated by the atomic force microscopy (AFM). The results show
those porous films have high thermal conduction to the purpose. At the same time, they had transferred
heat and limited work temperature, about 70℃, of HPLEDs successfully.
The amplitude of terahertz radiation (THz) from a series of oxide films on GaAs was measured by time resolved THz
emission system. The barrier heights and the densities of the interfacial states are determined from the PR intensity as a
function of the pump power density. The oxide-GaAs structures fabricated by in situ molecular beam epitaxy exhibit low
interfacial state densities in the range of 1011 cm-2. It is found that the amplitude of THz radiation from Al2O3-,
Ga2O3-,
and Ga2O3(Gd2O3)-GaAs structures are increases with interfacial electric field. The reason is that the electric field is
lower than the "critical electric field", the amplitude is proportional to the product of the electric field and the number of
photo-excited carriers. However, as the field higher than the critical electric field, sample of air-GaAs structure, the lower
THz amplitude was obtained due to the maximum drift velocity declines slightly as the field increases.
Room temperature photoreflectance (PR) was used to investigate the energy gaps transition, the surface state densities
and the surface barrier height of InxAlyGa1-x-yAs, in a series of epitaxial surface intrinsic-n+ structures with different Al
concentration. Features of Franz-Keldysh oscillations originating from the built-in electric field in the intrinsic top layer
were observed. Based on the thermionic emission theory and current-transport theory, the surface state density can be
determined from the square of maximum electric field as a function of various pump beam flux intensities.
Heat transfer has the important influence in quantum effect of light emitting diode (LED). In the
industrial processing, the quality of the thermal dissipation decides by the gumming technique between
the printed circuit board (PCB) and aluminum plate. Because it transfers the heat from electric device
to the aluminum plate which removes the heat. In this work, the alumina nitride (AlN) thin film
soldered the LED lamps to enhance the heat transfer. The films were fabricated onto 1070 aluminum
substrate by vacuum sputtering and plasma spraying technologies individually. The dielectric coatings
were characterized by several subsequent analyses, especially the real temperature measurement of
dielectric coating films. The X-Ray diffraction (XRD) diagram analysis reveals that ceramic phase can
successfully grow on the individual substrate. The studied results show that AlN thin film fabricated by
vacuum sputtering has low sheet resistivity, high hardness, high critical load, and good thermal
conduction (200 W/m-K); but, the same of coating fabricated by plasma spraying technology had the
best heat transfer as compared to the other samples.
Poly-p-phenylenebenzobisoxazole (PBO) and carbon nanotube (CNT) contain fully conjugated rodlike backbone entailing excellent mechanical properties, thermo-oxidative and solvent resistance. Rigid-rod PBO is commonly processed by dissolved in methanesulfonic acid or Lewis acid. A CNT of multi-wall carbon nanotube (MWNT) was dissolved in a Lewis acid solution of PBO for dispersion of nanotube, and then spun for thin film. MWNT
concentration in the films was from zero up to 5 wt.%. Compared to that of pure PBO film, all PBO/MWNT composite films retained same but enhanced UV-Vis absorption peaks showing that MWNT and PBO do not have overlapping electron orbitals affecting their energy gaps. The composite films were excited at 325 nm using a He-Cd
laser for photoluminescence (PL) response. All PL spectra had maximum wavelength peak at 540 nm indicative of yellow-green light emission. In the case of light emitting diodes, MWNT doped PBO would decrease threshold voltage for about 2 V and increase device emission current up two orders of magnitude than those without MWNT. This required a larger bias voltage leading to a shorter device lifetime.
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