A novel hyperbranched zinc phthalocyanine dye, i.e. HBZnPc-COOH, was synthesized, characterized, and applied into
dye-sensitized solar cells (DSSCs) as TiO2 sensitizer. UV-visible absorption, steady-state fluorescence, femtosecond
time-resolved fluorescence, cyclic voltammetry, current–voltage characteristics, and photoelectrical properties of the
active material/device were investigated. The utilization of hyperbranched structure was proved to be able to solve the
aggregation issue of phthalocyanine dyes on TiO2 surface which has been widely considered as one of the key limiting
issues that severely lower the efficiencies of phthalocyanine dye sensitized solar cells. With appropriate highest occupied
molecular orbital and lowest unoccupied molecular orbital energy levels, HBZnPc-COOH exhibited efficient and
ultrafast multi-phasic electron injection from both the Soret band and Q band to the conduction band of TiO2, leading to
a solar cell power conversion efficiency of 1.15% and a high incident photon to current conversion efficiency of 66.7%
at 670 nm.
Intrinsic ZnO (i-ZnO) thin films were deposited on glass substrates by radio-frequency magnetron sputtering for exploring the effects of the deposition conditions. These films were optically, electrically, and structurally characterized. Results showed that the properties of i-ZnO thin films changed with the changing of deposition conditions. These i-ZnO films were also integrated into CuIn1−xGaxSe2 (CIGS) solar cells. It was found that the incorporation of an i-ZnO layer in CIGS solar cells led to a significant improvement of homogeneity and efficiency of CIGS solar cells. An increment of 1.71% was gained in the average cell efficiency through adjusting the deposition conditions of i-ZnO layers. Detailed analysis showed that there was no improvement in cell efficiency under the deposition conditions favorable for growing the i-ZnO films. These results indicate that there should be a balance among the optimized performance of each layer deposited for high quality multi-layer devices.
Nonlinear optical properties of a series of protonated mixed (porphyrinato)(phthalocyaninato) rare-earth double-decker
complexes [MIIIH(TClPP){Pc(α-OC4H9)8}] (1-6;
M = Sm, Eu, Tb, Y, Ho, Lu; TClPP = meso-tetrakis
(4-chlorophenyl)porphyrinate; Pc(α-OC4H9)8 =
1,4,8,11,15,18,22,25-octakis(1-butyloxy)phthalocyaninate) in
dichloromethane were studied by using Z-scan technique with the fundamental laser emission at 800 nm from a
Ti:sapphire femtosecond laser system under different incident laser intensities. All these complexes showed strong
reverse saturable absorption related to the excited singlet population in a simple three-energy-level model which was
established for the interpretation of the experimental results. Both the linear and effective nonlinear absorption
coefficients of these complexes decreased approximately following the ionic radius contraction sequence of the rareearth(
III) cations within these complexes under the same situations. The effective excited-state absorption cross sections
were determined as well.
Third-order nonlinear optical properties of three isomeric tetrapyrrole triads, i.e. mixed (porphyrinato)(phthalocyaninato)
yttrium double-decker complexes appended with one metal free porphyrin chromophore at the para, meta, and orthoposition, respectively, of one meso-phenyl group of the porphyrin ligand in the double-decker unit through ester linkage,
3-5, were comparatively investigated along with the model compounds metal free meso-tetrakis(4-tert-butylphenyl)
porphyrin H2TBPP (1) and mixed [meso-tetrakis(4-tert-butylphenyl)porphyrinato]
[1,4,8,11,15,18,22,25-octakis(butyloxyl)phthalocyaninato] yttrium double-decker complex YIIIH(TBPP)
[Pc(α-OC4H9)8] (2) by using
Z-scan technique with the fundamental (800 nm) laser emission from a Ti:sapphire femtosecond laser system. Strong reverse
saturable absorption (RSA) properties of complexes 2-5 were observed. Interestingly, under highly intense irradiation, an
RSA-SA-RSA-SA-RSA switch behavior was evolved in the tight focal intensity regime on the Z-scan profiles of
complexes 3-5. Under the laser irradiation with focal intensity of 7.48-8.39 GW.cm-2, the triads 3 and 4 with the metal
free porphyrin chromophore appended at the para or meta positions of the meso-phenyl group of the porphyrin ligand in
the double-decker unit retained a characteristic response of RSA. In contrast, the triad 5 with the metal free porphyrin
chromophore appended at the ortho position has already shown a trend of SA peaks at the same intensity range,
revealing the effect of the position of porphyrin-substituent on the nonlinear optical properties of the triads.
KEYWORDS: Sensors, Fiber optics sensors, Absorption, Cladding, Active remote sensing, Fiber optics, Signal attenuation, Optical fibers, Refraction, Chemical species
This paper reports the development of a reversible fiber optic leak sensor capable of detecting the presence and the
concentration of traces of hydrazine. The sensor operates in the lowest attenuation wavelength range of commercial
silica fibers. The sensing material utilized in this sensor is a mix of organic compounds that contains
pentacenediquinone (PDQ) as an active sensing element. The index of refraction of this mix is adjusted to closely match
that of fiber's silica core. In the absence of hydrazine this mix exhibits a weak absorption in the near-infrared. When the
PDQ reacts with hydrazine, oxygen atoms from the PDQ are replaced by a molecule of hydrazine resulting in water as a
by-product. This replacement significantly increases the absorption of the mix specifically at wavelength between 1310
and 1430 nm. This absorption was found to be proportional to hydrazine gas concentration. The reaction however is a
self-reversible i.e. in the presence of water; the by-products of the reverse reaction would be PDQ and hydrazine.
A modified cladding fiber sensor was fabricated by replacing part of cladding with the PDQ sensing mix. Due to
evanescence-wave absorption by the modified sensing cladding, the optical signal passing through this sensor exhibited
a reversible intensity change in the presence hydrazine at different concentrations. Sensor's percentage response
magnitude and response time were found to be proportional to HZ gas concentration. Hence, in addition to low loss
operating wavelength advantage, this sensor is capable not only to detect HZ presence of but also its concentration.
Cu2ZnSnS4 (CZTS) was obtained from a sol-gel precursor which consists of copper chloride, zinc chloride, tin chloride, and thiourea. CZTS thin films were prepared by spin-coating the sol-gel precursor followed by annealing in a nitrogen atmosphere. The morphology, composition, and structure of the absorber layer were studied by scanning electron microscopy, energy dispersive spectroscopy, x-ray diffraction, and Raman scattering. The optical measurement shows the bandgap of these films is ∼1.51 eV, and the optical absorption coefficient is on the order of 104 cm−1. CZTS solar cells with a structure of low-alkali glass/Mo/CZTS/CdS/i-ZnO/ZnO:Al/Al grid were tentatively fabricated. The best solar cell showed a short-circuit current density of 5.06 mA/cm2, an open-circuit voltage of 358 mV, a fill factor of 34.66%, and an efficiency of 0.63% under AM1.5 (100 mW/cm2) illumination. These results demonstrate the CZTS thin films were successfully deposited by a cheap sol-gel technique.
KEYWORDS: Solar cells, Absorption, Luminescence, Scanning electron microscopy, Energy efficiency, Dye sensitized solar cells, Carbon, Resistance, Picosecond phenomena, Organic semiconductors
Organic-inorganic hybrid solar cells with a cell structure of indium tin oxide/TiO2/TiOx:hyperbranched phthalocyanine/CuSCN/Au (or carbon) have been fabricated by solution based processing using three hyperbranched phthalocyanines (H2PPc, TiOPPc and CuPPc) as light-absorbing materials. These organic-inorganic hybrid solar cells are extremely thin absorber solar cells, which possess p-i-n heterojunctions ("i," an intrinsic absorber layer), as they were confirmed by scanning electron microscopy. With an illuminated area of 1 cm2, a solar cell made from H2PPc achieved conversion efficiency of 0.23% under 1-sun air mass 1.5 global illumination. The lower conversion efficiency for the cell made from CuPPc was likely due to the energy loss in the formation of triplet states with an intersystem crossing time of 0.76 ps.
This paper reports the development of a hydrazine fiber optic reversible sensor that operates, for the first time to our
knowledge, in the lowest attenuation wavelength range of commercial silica fibers. A pentacenediquinone (PDQ) and
polymer mix, with an index of refraction adjusted to closely match that of silica, was used as an active sensing material
replacing the cladding of a silica core optical fiber. The optical signal passing through this modified cladding type fiber
sensor exhibited a reversible intensity change in the presence hydrazine at different concentrations.
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