Block copolymers containing pendant pyrene, terpyridine and poly(3-
hexylthiophene) moieties with different block ratios and chain lengths were
synthesized by reversible addition-fragmentation chain transfer (RAFT)
polymerization. The block copolymers obtained had narrow molecular weight
distribution. The applications of these polymers for non-covalent functionalization
of carbon nanotubes and in photovoltaic devices were studied.
The molecular weight distribution and block sizes of the block copolymers
could be controlled quite well. The polydispersities measured were below 1.25.
The block copolymers could be functionalized on the surface of CNTs. The
functionalized CNTs had an improved dispersing ability and a maximum
dispersing ability of 0.30 mgmL-1 in DMF was achieved. The photosensitizing
properties of an individual functionalized CNT were studied by conductive atomic
force microscopy. In the presence of the photosensitizing unit, the photocurrent
was measured to be 6.4 nAμW-1 at 580 nm. This suggests the role of metal
complexes in the photosensitizing process in the block copolymer.
Poly(3-hexylthiophene)-block-pendant pyrene copolymers were synthesized by
Grignard metathesis and RAFT polymerization. Different loadings of the block
copolymers functionalized CNT were employed as the electron accepting
materials in bulk heterojunction photovoltaic devices. A maximum power
conversion efficiency of 0.77 × 10-3 % was achieved for the poly(3-
hexylthiophene): 0.5% polymer functionalized CNT devices. The poor efficiency
was attributed to the low CNT loadings that limited the electron transport in the
devices.
The poly(3-hexylthiophene)-block-pendant pyrene copolymer were employed as
compatibilizer for poly(3-hexylthiophene): [6,6]-phenyl-C61-butyric acid methyl
ester (PCBM) bulk heterojunction photovoltaic devices. With the addition of 20
% of the block copolymer, a maximum power conversion efficiency of 1.62 %
could be achieved. The long term stability of the encapsulated photovoltaic
devices was studied. There was more than 30 % reduction in the degradation of
performance after 30 days when the block copolymer was added as compatibilizer.
These results suggested the role of the block copolymer compatibilizers in
improving both the photovoltaic performances and stability of the devices.
Differential scanning calorimetry results suggested that the improved photovoltaic
performances may be attributed to the enhanced compatibility between poly(3-
hexylthiophene) and PCBM. / published_or_final_version / Chemistry / Doctoral / Doctor of Philosophy
| Identifer | oai:union.ndltd.org:HKU/oai:hub.hku.hk:10722/183040 |
| Date | January 2012 |
| Creators | Li, Chi-ho, 李志豪 |
| Publisher | The University of Hong Kong (Pokfulam, Hong Kong) |
| Source Sets | Hong Kong University Theses |
| Language | English |
| Detected Language | English |
| Type | PG_Thesis |
| Source | http://hub.hku.hk/bib/B47869379 |
| Rights | The author retains all proprietary rights, (such as patent rights) and the right to use in future works., Creative Commons: Attribution 3.0 Hong Kong License |
| Relation | HKU Theses Online (HKUTO) |
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