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We investigate the characteristics of Cu2OO thin films deposited through the addition of N2O gas. The addition of N2O gas has remarkable effects on the phase changes, resulting in improved electrical and optical properties. An intermediate phase (6CuO·Cu2O) appears at a N2O flow rate of 1 sccm, and a Cu2OO (200) phase is then preferentially grown at a higher feeding amount of N2O. The optical and electrical properties of Cu2O thin films are improved with a sufficient N2O flow rate of more than 15 sccm, as confirmed through various analyses. Under this condition, a high bandgap energy of 2.58 eV and a conductivity of 1.5×10-2 S/cm are obtained. These high-quality Cu2OO thin films are expected to be applied to Cu2OO-based heterojunction solar cells and optical functional films. [ABSTRACT FROM AUTHOR]

In this work, buffer layers with various conditions are inserted at an n/i interface in hydrogenated amorphous silicon semitransparent solar cells. It is observed that the performance of a solar cell strongly depends on the arrangement and thickness of the buffer layer. When arranging buffer layers with various bandgaps in ascending order from the intrinsic layer to the n layer, a relatively high open circuit voltage and short circuit current are observed. In addition, the fill factors are improved, owing to an enhanced shunt resistance under every instance of the introduced n/i buffer layers. Among the various conditions during the arrangement of the buffer layers, a reverse V shape of the energy bandgap is found to be the most effective for high efficiency, which also exhibits intermediate transmittance among all samples. This is an inspiring result, enabling an independent control of the conversion efficiency and transmittance. [ABSTRACT FROM AUTHOR]

We demonstrate semitransparent organic photovoltaics (OPVs) based on thin metal electrodes and polymer photoactive layers consisting of poly(3-hexylthiophene) and [6,6]-phenyl C61 butyric acid methyl ester. The power conversion efficiency of a semitransparent OPV device comprising a 15-nm silver (Ag) rear electrode is 1.98% under AM 1.5-G illumination through the indium-tin-oxide side of the front anode at 100 mW/cm2 with 15.6% average transmittance of the entire cell in the visible wavelength range. As its thickness increases, a thin Ag electrode mainly influences the enhancement of the short circuit current density and fill factor. Its relatively low absorption intensity makes a Ag thin film a viable option for semitransparent electrodes compatible with organic layers. [ABSTRACT FROM AUTHOR]

Hydrogenated intrinsic Si (Si:H) thin films were deposited by a plasma-enhanced chemical vapor deposition technique, and the effect of the SiH4 flow rate ([SiH4]) and hydrogen dilution ratio (R) on the crystalline phase transition was studied using Raman spectroscopy and high-resolution transmission electron microscopy. The crystalline volume fraction (Xc) was strongly affected by [SiH4] as well as R, and higher Xc could be achieved by using a lower [SiH4] at the same R. The dependence of phase transition on the crystallinity of the under-lying layer was also investigated by depositing Si:H films on various substrates. To evaluate the effects of [SiH4] and R on the quality of amorphous-Si:H (a-Si:H) films, etch rates and absorption coefficients were obtained by an H2-plasma etching process and UV-Vis spectrophotometry, respectively. Even under the deposition condition resulting in a-Si:H films, the deposition rate decreased by a factor of 3 to 4.6, and the film density considerably increased as R increased from 4 to 19. On the other hand, the absorption coefficient very slightly decreased with R. The presence of microcrystalline Si:H could be observed only from the samples deposited with R>19 when the film was deposited on amorphous substrate. [ABSTRACT FROM AUTHOR]

TixSi1-xOy (TSO) thin films are fabricated using plasmaenhanced atomic layer deposition. The Ti content in the TSO films is controlled by adjusting the sub-cycle ratio of TiO2 and SiO2. The refractive indices of SiO2 and TiO2 are 1.4 and 2.4, respectively. Hence, tailoring of the refractivity indices from 1.4 to 2.4 is feasible. The controllability of the refractive index and film thickness enables application of an antireflection coating layer to TSO films for use as a thin film solar cell. The TSO coating layer on an Si wafer dramatically reduces reflectivity compared to a bare Si wafer. In the measurement of the current-voltage characteristics, a nonlinear coefficient of 13.6 is obtained in the TSO films. [ABSTRACT FROM AUTHOR]

AlxTi1-xO (ATO) films were grown by plasma-enhanced atomic layer deposition, using alternating Al2O3 and TiO2 cycles. The Ti content of the films showed a gradual increase as the number of TiO2 subcycles increased. The permittivity and refractive index gradually increased and the breakdown fields of ATO films decreased as the Ti content increased. The film growth is strongly dependent on the surface material in the ALD process; thus, this effect was considered when inducing the film growth rates of Al2O3 and TiO2 on the surface of ATO films. The growth rates of Al2O3 and TiO2 were dependent on the Ti content in the ATO films. Because of the low adsorption rate of Al precursors on the surfaces of the TiO2 films compared to on that of the Al2O3 films, the growth rate of the Al2O3 films on the TiO2 films was much lower than that on the surfaces of the Al2O3 films. With volume concentrations and a simple formula related to the refractive index, the refractive index of the ATO films was induced, which was in good agreement with the experimental results. [ABSTRACT FROM AUTHOR]