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Higher performance is expected in electronic devices that utilize metal oxide semiconductors in vertical architecture owing to the direct and effective electron transport. Producing anatase phase vertical TiO2 nanowires on conductive substrate has been challenging. Herein we demonstrate for the first time not only the facile fabrication of vertical arrays of anatase TiO2 nanowires, but also fabricating the wires by using electrospinning method. Firstly aligned nanofiberous TiO2 ribbons were produced by electrospinning and then erected to vertical nanowires after the post-treatment. As-produced vertical ceramic TiO2 nanowires possessed the area of 0.2 cm2 with wire diameter of 90 ± 30 nm, and height up to 27 μm. This approach can be a better alternative to the currently available methods like hydrothermal synthesis and template assisted fabrication as the diameter, height of the wires, and spacing between the wires can be effectively controlled by this method. With vertical nanowires of anatase phase TiO2 as photoelectrode in dye sensitized solar cells (DSSC), the solar-to-current conversion efficiency (η), short circuit current (Jsc), open circuit voltage (Voc), and fill factor (FF) were measured as 2.87% and 5.71 mA cm−2, 0.782 V, 64.2% respectively.

Two new D-pi-A sensitizers (L101 and L102) incorporating 5H-[1,2,5]thiadiazolo [3,4-f] isoindole-5,7(6H)-dione and 6H-pyrrolo[3,4-g]quinoxaline-6,8(7H)-dione core structures were synthesized and tested in liquid dye-sensitized solar cells (DSCs). L102 achieved a promising power conversion efficiency (PCE) of 6.2% (AM 1.5, 100 mW cm(-2)).

We report a regenerative iron oxide nanorod solar cell sensitized with squarine (SQ02) dye, which improves the overall light harvesting due to the dye's complementary absorption. The use of illumination sources which enabled selective excitation of Fe2O3 and the dye independently allowed the decoupling of transport and light absorption in Fe2O3. From absorbed photon-to-current conversion efficiency (APCE) calculations, it was found out that about 80% (at lambda = 680 nm) of the absorbed photons in SQ02 dye are converted to electrons and transported without any further loss into the FTO electrode. Impedance spectroscopy revealed that bulk recombination is still a prominent problem while utilizing hematite as a photoanode in a dye sensitized configuration.

The effect of TBP on Co(II/III) redox electrolyte was examined. Photocurrent of the device can be limited in electrolyte with high TBP concentration due to its viscous nature. The higher amount of TBP in electrolyte increases the viscosity of electrolyte and consequently slows down the diffusion of Co-III species. This is a unique observation for Co(II/III) electrolyte which is not observed in I-/I-3(-) electrolyte. An increase in TBP concentration from 0.1 to 0.5 M in a cobalt electrolyte containing 0.1 M Co(bpy)(3)(TFSI)(2) and 0.033 M Co(bpy)(3)(TFSI)(3) produced a 90 mV improvement in open-circuit potential (V-oc). Using electrochemical impedance spectroscopy (EIS), this enhancement could be attributed to the reduced interfacial recombination (33%) as well as a negative shift in the conduction 0 band level of TiO2 (67%). Although the influence of TBP in iodide/triiodide and cobalt-complex electrolytes is similar, the increase of viscosity at relatively high concentration of TBP in Co electrolyte should be taken into consideration in order to accomplish high efficiency DSCs based on Co-complex electrolytes.

In recent research in clean energy applications, clay has gained significant interest, especially as a gelator in dye-sensitized solar cells (DSSCs), for its capability to resolve the leakage issue of liquid electrolyte. In this paper, anionic hydrotalcite is utilized as a gelator to assist the formation of gel electrolyte in DSSCs. Three types of hydrotalcite with exchangeable anions, viz. NO3- (CL-N), CO32- (CL-C) and SO42- (CL-S), were synthesized with similar morphologies via the co-precipitation method. It is observed that the gel formation of hydrotalcite strongly depends on the exchangeable anions present in the hydrotalcite. The objective of this work is to understand the effect of hydrotalcite anions on the photovoltage and the photocurrent in the gel electrolyte through electrochemical analysis. With increasing ion affinity, the V-oc increases. This is attributed to Li+ intercalation with hydrotalcite compound resulting in the elevation of the conduction band of TiO2. With increasing ion affinity, the J(sc) decreases. This is attributed to the decreasing diffusion coefficient of triiodide and the increasing difficulty in the injection process. For anions with low ion affinity in hydrotalcite, the diffusion of the redox couple is not significantly affected by the high viscosity of the gel. Furthermore, the study indicates that proper selection of hydrotalcite compounds not only produces a quasi-solid gel electrolyte, but also increases the efficiency of the solar cells: the device performance was improved from 7.8% (liquid electrolyte) to 8.4% (hydrotalcite gel electrolyte).

Many candidate materials for photoelectrochemical water splitting will be better employed by decoupling optical absorption from carrier transport. A promising strategy is to use multiple thin absorber layers supported on transparent, conducting materials; however there are limited such materials that are both pH stable and depositable on arbitrary high surface area substrates. Here we present the first 3D porous niobium doped tin oxide (NTO) electrodes fabricated by atomic layer deposition. After high temperature crystallization the NTO is transparent, conductive, and stable over a wide range of pH. The optimized films have high electrical conductivity up to 37 S/cm concomitant with a low optical attenuation coefficient of 0.99 mu m(-1) at 550 nm. NTO was deposited onto high surface area templates that were subsequently coated with hematite Fe2O3 for the photoelectrochemical water splitting. This approach enabled near-record water splitting photocurrents for hematite electrodes employing a host-guest strategy.