Crystalstructure and photoelectric conversion properties of eosin Y-adsorbing ZnO films prepared by electroless deposition

Applied Catalysis B: Environmental, Volume 189, 15 July 2016, Pages 51-55

Satoshi Nagaya, Hiromasa Nishikiori, Hideaki Mizusaki, Kosuke Sato, Hajime Wagata, Katsuya Teshima

Abstract:Eosin Y-adsorbing ZnO thin films were prepared on substrates by electroless deposition from aqueous solutions containing zinc nitrate, dimethylamine−borane, and eosin Y. The concentration of eosin Y in the solution changed the structure of the deposited ZnO particles on the substrate. In the absence of eosin Y in the solution, the ZnO crystals preferred to grow in the c-axis direction. In the presence of eosin Y in the solution, the orientation of the ZnO was in the a-axis direction. As the eosin Y concentration increased, the size of the ZnO crystallites decreased and they became aggregated due to a strong interaction between the eosin Y and the (0002) plane of the ZnO, and consequently, the film resistance increased due to their boundary. The electron injection efficiency increased due to the strong interaction although the electron transfer efficiency decreased. The ZnO crystallite size, eosin Y amount, and their interaction increased the energy conversion efficiency.

Intercalating purple membranes into 2D β-alanine crystals to enhance photoelectric and nonlinear optical properties

Journal of the Taiwan Institute of Chemical Engineers, In Press, Corrected Proof, Available online 13 April 2016

Hsiu-Mei Chen, Kai-Ru Jheng, An-Dih Yu, Chia-Chen Hsu, Jian Hung Lin

Abstract:β-Alanine crystals with addition of purple membranes (PM) containing photoactive bacteriorhodopsin were prepared and characterized. Adding PM slightly to the crystals caused neither significant changes in their shapes nor shifts in the FTIR, SAXS intensity, and XRD spectra of the mother crystal. However, the purple composite crystal had a lower initial decomposition temperature but also a higher final decomposition temperature than the colorless pure one. The AFM analysis revealed that the embedded PM patches had undergone dynamic transitions, and were intercalated between β-alanine crystal layers with native integrated planar conformations. Compared with the pure one, the composite crystal exhibited 10-fold stronger second harmonic intensities, which varied with the incident angle and polarization of the probe beam. Thousands-fold increases in anisotropic positive photoconductance were also observed with the composite crystal. The results suggest orientational arrangement of most PM patches within each crystal and demonstrate the feasibility of producing a novel composite crystal with improved photonic properties by adding PM.

Transparent conductors with an ultrathin nickel layer for high-performance photoelectric device applications

Materials Science in Semiconductor Processing, Volume 31, March 2015, Pages 334-339

Ju-Hyung Yun, M. Melvin David Kumar, Yun Chang Park, Joondong Kim

Abstract:A thin nickel (Ni) layer of thickness 5 nm was inserted in between the indium tin oxide (ITO) layers of thickness 50 nm each so as to increase the conductivity of ITO without affecting much of its transmittance nature. ITO layers with and without Ni film were prepared by reactive DC sputtering on both Si and glass substrates. The influence of Ni layer on the optical and electrical properties of prepared devices was investigated. Due to the insertion of thin Ni layer, the resistivity of ITO/Ni/ITO sample (3.2×10−4 Ω cm) was reduced 10 times lesser than that of ordinary ITO layer (38.6×10−4 Ω cm); consequently it increased the mobility of ITO/Ni/ITO device. The external and internal quantum efficiencies (EQE and IQE) of ITO/Ni/ITO device exhibited better performance when compared to ITO layer that has no Ni film. At wavelengths of 350 and 600 nm, the photoresponses of ITO/Ni/ITO device were predominant than that of reference ITO device. This highly conductive and photoresponsive Ni inserting ITO layers would be a promising device for various photoelectric applications.

Durability and photo-electric characteristics of a mille-feuille structured amorphous selenium (a-Se)–arsenic selenide (As2Se3) multi-layered thin film

Journal of Non-Crystalline Solids, Volume 378, 15 October 2013, Pages 96-100

I. Saito, T. Masuzawa, Y. Kudo, S. Pittner, T. Yamada, A.T.T. Koh, D.H.C. Chua, Y. Mori, D.R.T. Zahn, G.A.J. Amaratunga, K. Okano

Abstract:A mille-feuille structured amorphous selenium (a-Se)–arsenic selenide (As2Se3) multi-layered thin film and a mixed amorphous Se–As2Se3 film is compared from a durability perspective and photo-electric perspective. The former is durable to incident laser induced degradation after numerous laser scans and does not crystallise till 105° of annealing, both of which are improved properties from the mixed evaporated film. In terms of photo-electric properties, the ratio between the photocurrent and the dark current improved whereas the increase of the dark current was higher than that of As2Se3 due to the unique current path developed within the mille-feuille structure. Implementing this structure into various amorphous semiconductors may open up a new possibility towards structure-sensitive amorphous photoconductors.

Performance evaluation of a photoelectric–thermoelectric cogeneration hybrid system

Solar Energy, Volume 118, August 2015, Pages 276-285

Bruno S. Dallan, Joseph Schumann, Frédéric J. Lesage

Abstract:The current state-of-the art in photovoltaic technology observes that the photoelectric conversion efficiency decreases with increasing material temperature. A proposed solution is to use the thermoelectric effect as a heat pump to manage the excess thermal energy of a photovoltaic cell. Previous investigations into photoelectric–thermoelectric hybrid systems have been either limited to theoretical analyses or experimental set-ups in which external refrigeration pumps are employed or an external heat source – other than photoelectric waste-heat – is used to drive the thermoelectric effect. The present work experimental investigates the viability of converting photoelectric waste-heat into electricity by way of the thermoelectric effect in an effort to better manage a photovoltaic module’s conversion efficiency. To this end, the electrical performance of a photovoltaic module and a thermoelectric module which are thermally in series is reported and discussed.