The first is a bias towards electrification. The majority of rural energy projects are focused on electrification. While electricity is an important driver of development, there is evidence that the main energy need for economic development in rural areas is heat energy. Currently, no organizations active in rural energy provision plan for the supply of electricity and heat energy in an integrated way. I will demonstrate how this leads to poor technology choice for rural energy provision, which does not meet people’s real needs.

The second bias is a gender bias. I will demonstrate that the tools we use to select renewable energy technologies for meeting rural energy needs have a gender bias built into them. This is because these tools have no means to account for the economic value of women’s work and time expended in collecting fuelwood and cooking using inefficient cookstoves and poor fuel sources.

By correcting for the separation between electrification and traditional energy, and for the gender bias, I believe it is possible to design rural energy planning tools that meet people’s needs effectively and efficiently.

RANDALL H. GOLDSMITH

Department of Chemistry
Northwestern University
Optimization of Long Range Electron Transfer for Solar Energy
Advisors: M. R. Wasielewski & M. A. Ratner

Electron transfer (ET) is a critical process in nano-scale electronic and photonic devices including solar cells. Like many natural phenomena, electron transfer is a complex function of many system-specific variables. Our approach entails the synthesis of organic molecules with specific electron donors and acceptors fixed at a well defined distance about an intervening molecule that covalently bridges the donor and acceptor. Using the versatility of organic chemistry to design molecular structures and the probing power of ultrafast transient absorption and nanosecond transient electron spin resonance spectroscopy, we study ET rates as a function of molecular structure, while keeping as many system variables as possible constant and changing only the variable of interest. This procedure allows a logical and methodical approach to studying ET. Most importantly, this effort has the potential to impact the use of organic photovoltaics. Organic photovoltaics have already been shown to possess huge advantages in terms of cost and facile large surface area coverage. However, their efficiency is still lacking, and only by conducting basic research to improve the efficiency of these devices that have ET as their basic step, can organic solar cells fulfill their promise to produce a significant fraction of the world’s energy needs.

ALEX BRANDON FLETCHER MARTINSON

Department of Chemistry
Northwestern University
Efficient Organic Photovoltaics that are Interlaced on the
Molecular Scale
Advisor: Joseph T. Hupp

The global need for affordable, clean energy has spurred interest in organic-based solar cells due to their potential for low-cost manufacturing. The dissociation of excitons into electrons and holes occurs at the interface between two dissimilar organic materials. Efficient photovoltaics must be made thick enough to absorb the majority of incident light, but paradoxically, a thicker absorbing layer decreases the chance that an exicton will reach the heterojunction. Recent efforts in our lab have produced a series of disphosphonic acid chromophores, including a chlorophyll-like macromoleclar square and an electron accepting perylene. Using established zirconium phosphonate chemistry, these molecules have recently been assembled in our lab into well-organized thin films on transparent conductive substrates. Films of each chromophore prepared using layer-by-layer assembly demonstrate control of thickness on the molecular level. More importantly, films of the macromolecular square have been found to be permeable to molecules as large as 16 Å. The molecular width of the perylene is only 6Å, which allows for facile assembly of this material within an assembled film of the electron donating macromolecular square. In this manner, a maximal heterojunction area is achieved between the organic materials to create an interlaced structure on the molecular level.