Interface and Morphology Engineering for Organic Photovoltaics
Date Issued
2010
Date
2010
Author(s)
Lin, Ching
Abstract
In this study, we conducted multipronged research to address the key issues of organic solar cells; our accomplishments include (1) improved efficiency and stability of polymer solar cell (PSC) by developing a novel low-temperature film-forming process which can be used with halogen-less solvents, and (2) reduced charge recombination and enhanced charge transport in dye-sensitized solar cell (DSSC) by developing interface-modifying thin films formed by low-temperature atomic layer deposition processes. In our PSC work, we demonstrated a film-forming process invloving low-temperature drying (-5 oC) and subsequent annealing for the active layer composed of blended poly(3-hexylthiophene) (P3HT) and [6,6]-phenyl C61 butyric acid methyl ester (PCBM). The low-temperature process enhanced nucleation of P3HT crystals, producing ample PCBM/P3HT bulk-heterojunction area to improve the efficiency, and forming a P3HT crystal network which served as an immobile frame to prevent PCBM/P3HT phase separation and the corresponding device degradation. Moreover, the low-temperature process could be used with a halogen-less solvent, tetralin, to obtain PSCs with similar device performance as that with the typical halogen-containing solvents. In our DSSC work, we demonstrated significant reduction in charge recombination with a 1 A Al2O3 formed with atomic layer deposition (ALD) on the porous TiO2 electrode, and correlated the improvement to the increase in Fermi level caused by the ALD film. Additionally, we improved the efficiency of DSSCs made with low-temperature sintering by ~70% by overcoating the porous TiO2 electrode with a 2 nm TiO2 film grown by ALD, which had significantly higher electron mobility than the porous TiO2 electrode.
Subjects
Photovoltaic Devices
Conjugated Polymers
Organic Electronics
Solar Cells
Nanostructures
Atomic Layer Deposition (ALD)
SDGs
Type
thesis
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