Dye-sensitized Solar Cells: An Interdisciplinary Effort in Optimized Dyes and Oxide Morphology
Organic Chemistry and Materials Engineering
Faculty: Michael Heagy, Department of Chemistry and Paul Fuierer, Department of Materials and Metallurical Engineering
Project Description: Achieving efficient solar energy conversion on a large scale and at low cost poses a key technological challenge for the near future. Because organic compounds can in principle be tailored to a number of needs due to infinite variability, they have been utilized extensively in dye sensitized solar cells (DSSC), molecular organic solar cells (MOSC) and polymer organic cells mainly based on electrically conductive polymers. Students participating in our group during the REU summer session would be involved in an interdisciplinary project between chemistry and materials with the synthesis of new fluorophores for DSSC applications derived from 1,8-naphthalimides. These compounds possess redox potentials that fall within the optimum voltage required for efficient electron transfer from dye to metal oxide, because it is lower than that of the conduction band of TiO2 at –0.5 V. Specific aims for REU students involved in the synthetic component include the following: (1) anchoring groups, positioned as close as possible to shorten the distance between the skeleton of molecules and the electrode. (2) These anchoring groups should be introduced into the acceptor part instead of the donor part to facilitate the asymmetric charge separation and electron injection. A representative synthetic step is shown below:
Following the synthetic goals outlined briefly above, the dyes would then go onto photovoltaic measurements with our collaborative partner Dr. Paul Fuierer from the materials department for the point of attachment onto TiO2 nanopartices and light simulation experiments.
The performance (i.e. power output and efficiency) of DSSCs may be improved by engineering the material and microstructure of the solid semiconductor portion of the cell. Fuierer’s group is experimenting with novel texturing, as well as including particulates of multiple length scales (nano to micro) to optimize both surface area and connectivity of titania phase. They have recently acquired a solar simulator meeting ASTM standards for power density and uniformity which will allow measurement and comparison of the I-V response of experimental cells. The commercially available “N3” and or “Black” metalorganic dyes, however, are prohibitively expensive for construction of significant numbers of experimental cells. Coupling the synthesis capability of Dr. Heagy’s group to provide new (cheaper) organic dyes, with our materials processing approaches may lead to significant innovation in DSSC devices.
REU students working in with the Fuierer group in the Materials engineering department would be involved in the fabrication, characterization and testing of DSSCs. The student would learn skills such as tape casting, screen printing, annealing, x-ray diffraction, and electrical (I-V) measurements. Involvement in both the organic synthesis and materials portions of this project would provide exposure to all aspects of new photovoltaic device research and development.
