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https://ptsldigital.ukm.my/jspui/handle/123456789/499460Full metadata record
| DC Field | Value | Language |
|---|---|---|
| dc.contributor.advisor | Mohammad Hafizuddin Haji Jumali, Dr. | - |
| dc.contributor.author | Bandar Ali Abdulqader Al-Asbahi (P50317) | - |
| dc.date.accessioned | 2023-10-13T09:32:08Z | - |
| dc.date.available | 2023-10-13T09:32:08Z | - |
| dc.date.issued | 2013-05-30 | - |
| dc.identifier.other | ukmvital:74768 | - |
| dc.identifier.uri | https://ptsldigital.ukm.my/jspui/handle/123456789/499460 | - |
| dc.description | Technological advancement enables us to use many optoelectronic devices based on conjugated polymers. Unfortunately, these devices inherit several problems namely low electron mobility, high energy barrier and low luminance efficiency. The objectives of this research are enhancing the photophysical properties of poly (9,9'-di-n-octylfluorenyl- 2.7-diyl) (PFO) as well as improving optoelectronic properties of PFO-based light emitting diodes (LEDs). The effect of TiO2 nanoparticles (NPs) content on the photophysical and optoelectronic properties enhancement of PFO (with and without Fluorol 7GA) is demonstrated. The solution blending method was used to prepare the PFO/TiO2, PFO/Fluorol 7GA and PFO/Fluorol 7GA/TiO2 composites. Then, these composites solution were spin-coated onto glass and ITO substrates to produce composite thin films. Microstructure of the nanocomposites was determined using X-ray diffraction (XRD) while absorption and fluorescence spectra were recorded using UV-Vis and PL spectrophotometer, respectively. X-ray diffractograms confirmed the formation of PFO/TiO2 nanocomposites. The absorbance and fluorescence spectra of the PFO/TiO2 nanocomposite were proportionately enhanced with the content of TiO2 NPs. The recombination between electrons of TiO2 and holes of PFO, at the interface of PFO/TiO2 nanocomposites enhanced the luminescence properties. Besides, the energy gap, line width of emission intensity and vibronic spacing decreased. The line width of the energy gap tails, the vibronic transition intensity and S-factor increased resulted from higher aggregation of films as supported by field emission scanning electron microscope (FE-SEM) images. On the other hand, efficient non-radiative energy transfer between PFO as donor and Fluorol 7GA as acceptor has been proven in this work. Long range dipole–dipole interaction (Förster type) between the excited donor and ground state acceptor molecules was the dominant mechanism responsible for energy transfer as proven by large values of quenching rate constant (kSV), energy transfer rate constant (kET) and critical distance of energy transfer (Ro). The emission intensity in the acceptor side increased whereas that for the donor decreased with initial increment the Fluorol 7GA. Once Fluorol7GA exceeded the optimum ratio (0.5 wt. %), the emission intensity in the acceptor side started to reduce. Finally, Fluorol 7GA recorded the lowest emission once PFO completely quenched. The reduction in the emission intensity was attributed to the extra molecules of the acceptor acted as dark quencher. The incorporation of TiO2 NPs in the blend of PFO/Fluorol 7GA inhibited the formation of the dark quenchers as evidenced from absorption and photoluminescence spectra. Generally, the PFO/Fluorol 7GA/TiO2 OLED devices exhibited the best performance compared to other OLED devices (PFO/Fluorol 7GA and PFO/TiO2). The incorporation of the Fluorol 7GA into the emissive layer of the PFO/TiO2 OLED devices led to reduction of the negative effect of the high content of TiO2 NPs (30 and 35 wt. %). The maximum brightness was for TiO2 content of 25 wt. % into the PFO/0.5 wt. % Fluorol 7GA blend, whereas the maximum luminance efficiency was for 15 wt. % of the TiO2 NPs. This work successfully demonstrated that the combination between the donor/acceptor (PFO/Fluorol 7GA) blending and incorporation of nanostructure (TiO2 NPs) into the conjugated polymer (PFO) was presented as novel method to improve performance of the PFO-based LED devices.,Ph.D | - |
| dc.language.iso | eng | - |
| dc.publisher | UKM, Bangi | - |
| dc.relation | Faculty of Science and Technology / Fakulti Sains dan Teknologi | - |
| dc.rights | UKM | - |
| dc.subject | Organic | - |
| dc.subject | Light emitting diodes | - |
| dc.subject | Organic semiconductors -- Optical properties | - |
| dc.title | Photophysical and optoelectronic properties of poly (9,9'-Di-N-Octylfluorenyl-2.7-Diyl) (PFO)/Fluorol 7GA/TiO2 nanocomposites for organic light emitting diodes | - |
| dc.type | Theses | - |
| dc.format.pages | 174 | - |
| dc.identifier.callno | K7871.99.O74.A834 2013 | - |
| dc.identifier.barcode | 000310 | - |
| Appears in Collections: | Faculty of Science and Technology / Fakulti Sains dan Teknologi | |
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| File | Description | Size | Format | |
|---|---|---|---|---|
| ukmvital_74768+Source01+Source010.PDF Restricted Access | 4.51 MB | Adobe PDF |  View/Open |
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