Among various deposition techniques to deposit Cu2ZnSn(S,Se)4 (CZTSSe) thin films, solution-based processes have attracted considerable attention because of their potentially low cost. Most of the reported solution-based methods are based on nonaqueous solvents, such as hydrazine, and organic solvents. We report the deposition of CZTSSe thin films and fabrication of CZTSSe solar cells by a water-based, solution-processed method followed by Se vapor annealing. The effects of Se vapor feeding time on the properties of CZTSSe thin films and the performance of CZTSSe solar cells are investigated. The ratio of Se/(Se+S) can be tuned by changing the Se vapor feeding time. Our results indicate that extending the Se vapor feeding time increases the band gap, slightly increases the lattice constant, and significantly improves the morphologies of the CZTSSe thin films. A remarkable enhancement in the performance was observed from the CZTSSe solar cells annealed with a longer Se vapor feeding time compared with those without Se feeding.
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.
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.
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