Morphology Evolution Of ZnO Thin Films Deposited By Nitrogen Mediated Crystallization Method

We study the surface morphology of ZnO thin films deposited by nitrogen mediated crystallization method utilizing atomic force microscopy as a function of nitrogen flow rates. Initially, the surface morphology of ZnO thin film deposited without nitrogen exhibits a bumpy surface with spiky grains where the skewness and kurtosis values were found to be 0.48 and 4.80, respectively. By addition of small amount of nitrogen, the skewness and kurtosis values of the films significantly decrease associated with a flatter topography. Further increase in nitrogen flow rate to 16 sccm has roughened the surface shown mainly by the increase in kurtosis value to be 3.30. These results indicate that the addition of small amount of nitrogen during deposition process has enhanced the adatoms migration on the surface resulting in a superior film with a larger grain size. Two-dimensional power spectral density analysis reveals that all the films have self-affine fractal geometry with total fractal values in the range of 2.14 to above 3.00

Polymer counter electrode of poly(3,4-ethylenedioxythiophene):Poly(4-styrenesulfonate) containing TiO2 nano-particles for dye-sensitized solar cells

A counter electrode of dye-sensitized solar cells (DSC) is an important component, which often limits the cell performance. Here we report a low-cost and high-performance polymer counter electrode of poly(3,4-ethylenedioxythiophene):poly(4-styrenesulfonate) (PEDOT:PSS) containing TiO2 nano-particles for dye-sensitized solar cells. Catalytic characteristics of the counter electrode are significantly improved by adding TiO2 nano-particles to PEDOT:PSS. This improvement is attributed to catalytic activation due to an increase in the surface area of the counter electrode and an increase in conductivity of PEDOT:PSS due to its structural change. A dye-sensitized solar cell using the polymer counter electrode shows 8.27% of efficiency and 16.39 mA cm(-2) of short circuit current density, higher than 7.59% of efficiency and 14.75 mA cm(-2) of short circuit current density of a cell with the conventional Pt counter electrode. (C) 2015 Elsevier B.V. All rights reserved

Impact of radish sprouts seeds coat color on the electron paramagnetic resonancesignals after plasma treatment

Recently, cold atmospheric plasma (CAP) treatment on seed germination has emerged as a useful technique to increase agriculture production,although, the mechanism of the cold plasma in seed germination is still under investigation. In this work, we studied the role of pigments in the seedcoat of radish sprouts on the electron spin resonance (ESR) signals before and after CAP treatment. Radish sprouts seeds having gray color showenhanced ESR signals after the CAP treatment, whereas, no increased ESR signals were observed for brown color seeds of radish sprouts ascompared to their respective control seeds. These results reveal that seeds from the same harvest year having different seed coat colors showdifferent responses to the plasma treatment. Although ESR signal intensity can vary with the harvest year, the change in ESR signal intensity afterplasma treatment depends on the seed coat color. Independently on the harvest year (2017 and 2018), CAP increased ESR signals stronger in thegrey seeds in comparison to the brown ones. The results indicated that seed coat color may be an important variable for understanding differencesin the extent of CAP effects on seedsBiochemijos katedraVytauto Didžiojo universiteta

Surface Modification of Polymer Counter Electrode for Low Cost Dye-sensitized Solar Cells

Poly(3,4-ethylenedioxythiophene):poly(4-styrenesulfonate) (PEDOT:PSS) was already used as a counter electrode material of dye-sensitized solar cells (DSCs) in other previous researches but its low catalytic activity has been a sticking point. Here we report the catalytic activation of PEDOT:PSS counter electrode by the surface modification using nano-particles. Nano-particle addition contributes to widening catalytic interface and improving catalytic characteristics of PEDOT:PSS counter electrode. However, only a few materials are applicable although various nano-particle materials were applied for the counter electrode of DSC. Catalytic characteristics of PEDOT:PSS counter electrodes with nano-particles are analyzed by cyclic voltammetry and electrochemical impedance spectroscopy. Finally, a DSC based on catalytically enhanced polymer counter electrode achieves 0.71 V of V-OC, 12.60 mA cm(-2) of J(SC), 0.75 of FF, and 6.65% of efficiency, and it is higher than 5.60% of efficiency of a DSC based on conventional Pt counter electrode. (C) 2016 Elsevier Ltd. All rights reserved

Performance comparison of nitrile-based liquid electrolytes on bifacial dye-sensitized solar cells under low-concentrated light

Abstract: Dye-sensitized solar cell (DSSC) has low power output and efficiency. Even though the low-concentrated light can increase the POUT and power conversion efficiency (PCE) of DSSC, the effect of increase in the cell temperature, particularly electrolyte evaporation, becomes a major concern. In this study, we compared and investigated the performance of acetonitrile (AN-50), propionitrile (PN-50), and 3-metoxy propionitrile (Z-100) as nitrile-based electrolyte under low-concentrated light. The results showed 4–8 times increase in JSC and POUT in all electrolytes. AN-50 demonstrated an improved performance under influence of 2 cm distance concave mirror concentrated light with the highest JSC = 74.21 mA/cm2, POUT = 24.53 mW/cm2, and η = 7.99. However, the performance of cell with AN-50 and PN-50 started to degrade within 3 h of measurement. In contrast, Z-100 displayed performance stability during 4 days measurement even with the lowest JSC= 49.98 mA/cm2, POUT = 19.50 mW/cm2, and η = 6.35. Graphical abstract: Figure not available: see fulltext

Highly conducting and very thin ZnO : Al films with ZnO buffer layer fabricated by solid phase crystallization from amorphous phase

We propose a novel method of oxide crystal growth via atomic-additive mediated amorphization. By utilizing this method, solid-phase crystallization (SPC) of ZnO from amorphous phase has been successfully demonstrated via nitrogen atom mediation. The resultant SPC-ZnO films are highly orientated and the crystallinity is higher than that of the films prepared by conventional sputtering. By using the SPC-ZnO as a buffer layer, the resistivity of ZnO:Al (AZO) films is drastically decreased. 20-nm-thick AZO films with a resistivity of 5 × 10^<-4> Ω cm and an optical transmittance higher than 80% in a wide wavelength range of 400-2500 nm have been obtained