Exotic Solar
  
 



Technology

 Exotic Solar's R&D team, in collaboration with the University of Utah's researchers, is actively involved in cutting edge research in renewable energy technology. A brief descriptions of some of the important projects is given below:


 Solid State Dye-Sensitized Solar Cells  
 
DSSCs based on liquid electrolytes have attained an impressive conversion efficiency of ~11%. But a major problem with these DSSCs is the evaporation and possible leakage of the liquid electrolyte from the cell. This limits the application of these cells and poses a serious problem in the scaling up of DSSC technology for practical applications. A current major focus of interest in this field is to fabricate Solid-State DSSCs (SS-DSSC) by using solid phase electrolytes such as molten salts, organic hole transport materials, and polymer electrolytes. However, most SS-DSSCs studied so far have suffered from the problems of short-circuit and mass transport limitations of the ions, resulting in low conversion efficiencies compared with the liquid version. Lately, the use of p-type semiconductors as hole-collectors in DSSCs has been proposed. But, because of the scarcity of suitable p-type semiconductors (having proper band-gap, valence band position and stability) very little progress has been made on SS-DSSCs. In this project we are utilizing a new p-type semiconductor oxide-CuBO2, recently invented in our laboratory, as a hole collector. Preliminary studies have shown that CuBO2 is very stable, has high electrical conductivity and carrier mobility, and at the same time its flat band potential is very suitable for separating electrons and holes in TiO2-based SS-DSSCs. Project has three major tasks: (i) Fabrication of DSSCs using p-type CuBO2 as a hole-collector; (ii) Development of strategies to employ coupled dye mixtures for enhanced light harvesting; and (iii) Understanding the charge injection and recombination dynamics in SS-DSSCs.Direct water splitting on a particulate photocatalyst using the sun is considered to be a potential way to produce hydrogen at a large scale. Research during the last few years has shown that metal oxide photocatalysts can be very effective for overall water splitting. However, still, most of the metal oxide photocatalysts developed to date only function in the ultraviolet (UV) region due to their large band gaps (>3eV). Although a number of photocatalysts driven by visible light have been proposed as potential candidates for this purpose, a satisfactory material has yet to be devised. Recently in our lab we have invented a new p-type semiconducting oxide CuBO2 which shows great promise for solar hydrogen production. It posses delafossite crystal structure and exhibits a direct bandgap of 3.2 eV and an indirect bandgap of 2.1 eV. Detailed photoelectrochemical measurements on this material showed that its valence band is located at ~5.2 eV below vacuum (0.46 eV vs. SCE), a value very well satisfying the condition for the photo-splitting of water. Inspired by potential of this material in this project, we are trying to utilize CuBO2 (and its nanocomposites with n-type oxides such as ZnO, TiO2, etc) for designing a commercial solar-hydrogen reactor which can produce hydrogen by direct splitting of water.

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 Solar-hydrogen using Dispersed Metal-Oxide Photoelectrodes (SS-DSSCs)  
 
Direct water splitting on a particulate photocatalyst using the sun is considered to be a potential way to produce hydrogen at a large scale. Research during the last few years has shown that metal oxide photocatalysts can be very effective for overall water splitting. However, still, most of the metal oxide photocatalysts developed to date only function in the ultraviolet (UV) region due to their large band gaps (>3eV). Although a number of photocatalysts driven by visible light have been proposed as potential candidates for this purpose, a satisfactory material has yet to be devised. Recently in our lab we have invented a new p-type semiconducting oxide CuBO2 which shows great promise for solar hydrogen production. It posses delafossite crystal structure and exhibits a direct bandgap of 3.2 eV and an indirect bandgap of 2.1 eV. Detailed photoelectrochemical measurements on this material showed that its valence band is located at ~5.2 eV below vacuum (0.46 eV vs. SCE), a value very well satisfying the condition for the photo-splitting of water. Inspired by potential of this material in this project, we are trying to utilize CuBO2 (and its nanocomposites with n-type oxides such as ZnO, TiO2, etc) for designing a commercial solar-hydrogen reactor which can produce hydrogen by direct splitting of water.

more