1 research outputs found
Understanding and Promoting Molecular Interactions and Charge Transfer in Dye-Mediated Hybrid Photovoltaic Materials
The performances of hybrid organic–inorganic
photovoltaics
composed of conjugated polymers and metal oxides are generally limited
by poor electronic coupling at hybrid interfaces. In this study, physicochemical
interactions and bonding at the organic–inorganic interfaces
are promoted by incorporating organoruthenium dye molecules into self-assembled
mesostructured conjugated polymer–titania composites. These
materials are synthesized from solution in the presence of surfactant
structure-directing agents (SDA) that solubilize and direct the nanoscale
compositions and structures of the conjugated polymer, dye, and inorganic
precursor species. Judicious selection of the SDA and dye species,
in particular, exploits interactions that direct the dye species to
the inorganic–organic interfaces, leading to significantly
enhanced electronic coupling, as well as increased photoabsorption
efficiency. This is demonstrated for the hydrophilic organoruthenium
dye N3, used in conjunction with alkyleneoxide triblock copolymer
SDA, polythiophene conjugated polymer, and titania species, in which
the N3 dye species are localized in molecular proximity to and interact
strongly with the titania framework, as established by solid-state
NMR spectroscopy. In contrast, a closely related but more hydrophobic
organoruthenium dye, Z907, is shown to interact more weakly with the
titania framework, yielding significantly lower photocurrent generation.
The strong SDA-directed N3-TiO<sub><i>x</i></sub> interactions
result in a significant reduction of the lifetime of the photoexcited
state and enhanced macroscopic photocurrent generation in photovoltaic
devices. This study demonstrates that multicomponent self-assembly
can be harnessed for the fabrication of hierarchical materials and
devices with nanoscale control of chemical compositions and surface
interactions to improve photovoltaic properties