2 research outputs found
A Pronounced Dispersion Effect of Crystalline Silicon Nanoparticles on the Performance and Stability of Polymer:Fullerene Solar Cells
We investigated the dispersion effect of crystalline
silicon nanoparticles
(SiNP) on the performance and stability of organic solar cells with
the bulk heterojunction (BHJ) films of polyÂ(3-hexylthiophene) (P3HT)
and [6,6]-phenyl-C<sub>61</sub>-butyric acid methyl ester (PC<sub>61</sub>BM). To improve the dispersion of SiNP in the BHJ films,
we attached octanoic acid (OA) to the SiNP surface via esterification
reaction and characterized it with Raman spectroscopy and high-resolution
transmission electron microscopy. The OA-attached SiNP (SiNP-OA) showed
improved dispersion in chlorobenzene without change of optical absorption,
ionization potential and crystal nanostructure of SiNP. The device
performance was significantly deteriorated upon high loading of SiNP
(10 wt %), whereas relatively good performance was maintained without
large degradation in the case of SiNP-OA. Compared to the control
device (P3HT:PC<sub>61</sub>BM), the device performance was improved
by adding 2 wt % SiNP-OA, but it was degraded by adding 2 wt % SiNP.
In particular, the device stability (lifetime under short time exposure
to 1 sun condition) was improved by adding 2 wt % SiNP-OA even though
it became significantly decreased by adding 2 wt % SiNP. This result
suggests that the dispersion of nanoparticles greatly affects the
device performance and stability (lifetime)
Doping Effect of Organosulfonic Acid in Poly(3-hexylthiophene) Films for Organic Field-Effect Transistors
We attempted to dope polyÂ(3-hexylthiophene) (P3HT) with
2-ethylbenzenesulfonic
acid (EBSA), which has good solubility in organic solvents, in order
to improve the performance of organic field effect transistors (OFET).
The EBSA doping ratio was varied up to 1.0 wt % because the semiconducting
property of P3HT could be lost by higher level doping. The doping
reaction was confirmed by the emerged absorption peak at the wavelength
of ∼970 nm and the shifted S2p peak (X-ray photoelectron spectroscopy),
while the ionization potential and nanostructure of P3HT films was
slightly affected by the EBSA doping. Interestingly, the EBSA doping
delivered significantly improved hole mobility because of the greatly
enhanced drain current of OFETs by the presence of the permanently
charged parts in the P3HT chains. The hole mobility after the EBSA
doping was increased by the factor of 55–86 times depending
on the regioregularity at the expense of low on/off ratio in the case
of unoptimized devices, while the optimized devices showed ∼10
times increased hole mobility by the 1.0 wt % EBSA doping with the
greatly improved on/off ratio even though the source and drain electrodes
were made using relatively cheaper silver instead of gold