Dye-sensitized solar cells (DSSCs) have the potential to be an inexpensive alternative to solar cells that use much more expensive components such as silicon. The fabrication of DSSCs that have significantly higher solar energy conversion efficiency could have a major impact on solar cell implementation. Currently, several factors limit increases in DSSC efficiency and their practical use, such as undesired electron recombination pathway, inefficient light harvesting, and high cost of rare earth-based (e.g. ruthenium) photosensitizers. DSSCs with novel multi-layered structures have potential to overcome the traditional thickness limitation for the TiO2 layer, and would enable efficient collection of electrons generated from multiple TiO2 layers.
The proposed research will explore the structure-efficiency relationships of DSSCs fabricated with a novel multi-layered structure motif. New approaches are proposed to create a multi-layered structure using atomic layer deposition. Furthermore, a proposed cyclization-anchoring strategy will be utilized to introduce 2-D or 3-D cyclic arrays of low-cost, hybrid organic photosensitizers with broad absorption bands into DSSCs to improve light harvesting. The proposed research will lead to better understanding of the structure-property relationships in multi-layered DSSCs, and may open up new approaches for the development of novel structure motifs for high-efficiency DSSCs.
Broader Impacts
This research project will provide cross-disciplinary training for one graduate student in chemistry and one graduate student in chemical engineering in renewable energy technologies. At least six undergraduate students will also participate in this interdisciplinary research program. The education and outreach plan will make a particular effort to recruit, work with, and encourage students from underrepresented groups.
For the 1st time, we successfully utilized alkyne metathesis, a highly efficient dynamic covalent chemistry approach, to construct a novel three-dimensional rectangular prismatic molecular cagen one step from a readily accessible porphyrin-based precursor. This structure consist of rigid, aromatic porphyrin (photosensitizer) and carbazole moieties as well as linear ethynylene linkers, rendering its shape-persistent nature. This structure shows a high selectivity and binding of C70 fullerenes over C61 fullerences with a selectivity greater than 1000. This is fully reversible under acid-base stimuli, thus allowing successful separation of C70 from a C60-enriched mixture. The binding of these molecular cages with fullerenes have potential to form complexes that can be active components in solar cells. Nano hybrid solar cells that consist of single-wall carbon nanotubes and molecular cage/fullerene complexes that were formed have the potential for understanding and improving the design of efficient nano hybrid-based, light harvesting photovoltaic devices. Dye sensitized solar cells that consist of layered structures to more efficiently utilize the electrons from solar exposure were created using atomic layer deposition, and cells with higher efficiency were created with this approach, indicating its potential application. However difficulties were encountered in obtaining reproducible solar cell structures, and this issue was not resolved during the time period of the grant.
