We report efficient organic bulk heterojunction solar cells, utilizing spray-patterned films of single-wall carbon nanotubes for the transparent electrode. High power conversion efficiencies of up to 3.6% were obtained using a blend of poly(3-hexylthiophene) and phenyl-C61 butyric acid methyl ester as the active layer, comparable to conventional devices utilizing indium tin oxide as the transparent electrode.
We report solution processed highly photosensitive thin film transistors (TFTs) based on poly(9,9-dioctylfluorene-cobithiophene)
(F8T2) as an active photoconducting material. Bottom gate contact coplanar device structure on Si wafer
transistors was used. The photosensitivity of the drain photocurrent was investigated for different F8T2 annealing
temperatures and illumination irradiances. Transistors annealed at 280<sup>o</sup>C show the highest drain current, approximately 8
times higher than the as-spincoated device at room temperature with a gate voltage of -40V. However, the field effect
mobilities in the saturation regime for all devices at different annealing temperatures are in the same order of ~10<sup>-4</sup>
cm<sup>2</sup>/Vs. The field effect mobilities of the transistors were not affected by illumination, but the drain photocurrent of the
transistor was significantly increased and the threshold voltage was shifted towards zero bias voltage when the polymer
absorbs photons. The measured maximum responsivity was ~18.5 A/W for an LED light source with a peak wavelength
of 465 nm and 19 nm bandwidth at 5 μW/cm<sup>2</sup> light intensity. This is so far the highest reported for F8T2
phototransistors. The characteristics of transistors dominated by the photoconductive effect (turn-off) as well as the
photovoltaic effect (turn-on) against a wide range of illumination intensities are reported.
We report that polymer light emitting diodes (pLEDs) and polymer photodetectors can be integrated on disposable polydimethylsiloxane [PDMS] microfluidic flowcells to form hybrid microchips for bioluminescence applications. PLEDs were successfully employed as excitation light sources for microchip based fluorescence detection of microalbuminuria (MAU), an increased urinary albumin excretion indicative of renal disease. To circumvent the use of optical filters, fluorescence was detected perpendicular to the biolabel flow direction using a CCD spectrophotometer. Prior to investigating the suitability of polymer photodiodes as integrated detectors for fluorescence detection, their sensitivity was tested with on-chip chemiluminescence. The polymer photodetector was integrated with a PDMS microfluidic flowcell to monitor peroxyoxalate based chemiluminescence (CL) reactions on the chip. This work demonstrates that our polymer photodetectors exhibit sensitivities comparable to inorganic photodiodes. Here we prove the concept that thin film solution-processed polymer light sources and photodetectors can be integrated with PDMS microfluidic channel structures to form a hybrid microchip enabling the development of disposable low-cost diagnostic devices for point-of-care analysis.
We report a low cost device for performing chemiluminescent (CL) assays in a miniaturised format. The device comprises a poly(dimethylesiloxane) microfluidic chip for performing the CL assay coupled to a polymer photodiode based on a 1:1 blend by weight of poly(3-hexylthiophene) [P3HT] and 1-(3-methoxycarbonyl)-propyl-1-phenyl-(6,6)C<sub>61</sub> [PCBM]. The integration of organic photodiodes with microfluidic chips offers a promising route to low cost fully integrated diagnostic devices for point-of-care applications.