Completed Exploratory Projects 2007

Research Areas & Activities Solar Energy Biomass Energy Hydrogen Advanced Combustion CO₂ Capture CO₂ Storage Advanced Materials & Catalysts Advanced Coal Advanced Transportation Advanced Electric Grid Grid Storage Other Renewables Integrated Assessment Advanced Nuclear Energy Geoengineering Exploratory Projects Completed Projects 2011 Completed Projects 2010 Completed Projects 2009 Completed Projects 2008 Completed Projects 2007 Completed Projects 2006 All Activities Analysis Activities Technical Reports

Research

Nanowire-Nanocrystal Multiexciton Solar Cells
Nanostructured ZnO as a Solution-Processable Transparent Electrode Material for Low-Cost Photovoltaics
Plasma Activated Fuel Cells
Feasibility of a Novel Photoelectrochemical Conversion Device

Nanowire-Nanocrystal Multiexciton Solar Cells

Investigators
Yi Cui, Materials Science and Engineering, Stanford University

Objective
This project explores a novel photovoltaic cell architecture using a network of PbSe nanowires combined with PbS nanocrystals. The aim of this project is to use the proposed structure to achieve both high photon absorption through impact ionization processes in the nanocrystals, and efficient charge transport through both the nanowire network and the nanocrystal arrays filling the void space in the nanowire scaffold. This concept is a new approach to the realization of high-efficiency thin film photovoltaics, and will require the exploration of fundamental questions, many of which will also benefit other innovative thin film technologies.

Publications

Zhu, J. H. Peng, C. K. Chan, and Yi Cui. “Hyperbranched lead selenide nanowire networks” Nano Letters, Vol 7, No. 4, 1095-1099, doi:10.1021/nl0700393 (2007).

Nanostructured ZnO as a Solution-Processable Transparent Electrode Material for Low-Cost Photovoltaics

Investigator
Alberto Salleo, Materials Science and Engineering, Stanford University

Objective
This study explores innovative approaches for using zinc-based oxide materials as transparent conductive films in photovoltaic devices. The proposed strategy consists of depositing a planar network of doped ZnO nanowires from solution and annealing it by laser to form a continuous film. This approach promises better conductivity and transparency properties than in unannealed nanowire networks, in addition to the advantages associated with solution processing. Laser annealing of highly-doped ZnO nanowires is a novel technique that will be investigated for the first time in this project.

Plasma Activated Fuel Cells

Investigator
Mark A. Cappelli, Mechanical Engineering, Stanford University
Objective
In this project, the effects of plasma injection on the operation of a fuel cell will be studied. A nonequilibrium plasma will be generated in the inlet gases of the fuel cell via dielectric barrier discharge. Ionized gas-phase species may alter the reaction pathways at the catalytic solid-gas interface in a way that affects significantly the activation losses. Through bench top experiments and systems-level modeling, this research will determine whether the resulting change in operational efficiency can overcome the power needed to generate the plasma. The applications of plasma to fuel cells extend beyond mere efficiency gains; plasma enhancement may also be used simultaneously for internal fuel reforming.

Feasibility of a Novel Photoelectrochemical Conversion Device

Investigator
Fritz B. Prinz, Mechanical Engineering and Materials Science and Engineering, Stanford University
Objective
This project envisions solar conversion systems where light is converted to electricity via charge separation and transfer through a solid-state electrolyte. The latter occurs through an ultra-thin solid state electrolyte which is capable of conducting redox couples that carry both positive and negative charges without allowing them to recombine within the confinements of the film electrolyte.

To effectively screen feasible material alternatives for this project, efficient computational tools are needed for the down selection process. Therefore this project also aims to develop a computational tool to calculate the electronic structure including the band gap of nano-scale devices with practical computational resources. The simulation tool under development will use a tight binding method that is shown to be fast enough to evaluate relevant systems with reasonable accuracy.

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