Non-Radiative Energy Transfer Mechanism and Optoelectronic Properties of (PFO/TiO2)/Fluorol 7GA Hybrid Thin Films

Energy transfer between poly (9,9'-di-n-octylfluorenyl-2,7-diyl) (PFO)/TiO2 nanoparticles (NPs), as a donor, and Fluorol 7GA as an acceptor has been studied. The energy transfer parameters were calculated by using mathematical models. The dominant mechanism responsible for the energy transfer between the donor and acceptor molecules was Förster-type, as evidenced by large values of quenching rate constant and critical distance of energy transfer as well as fluorescence quantum yield and excited state lifetime of donor in the presence of acceptor. Moreover, these composites, which were used as an emissive layer in organic light emitting diodes, were investigated in terms of current–voltage and electroluminescence spectra

Non-Radiative Energy Transfer Mechanism and Optoelectronic Properties of (PFO/TiO2)/Fluorol 7GA Hybrid Thin Films

Energy transfer between poly (9,9'-di-n-octylfluorenyl-2,7-diyl) (PFO)/TiO2 nanoparticles (NPs), as a donor, and Fluorol 7GA as an acceptor has been studied. The energy transfer parameters were calculated by using mathematical models. The dominant mechanism responsible for the energy transfer between the donor and acceptor molecules was Förster-type, as evidenced by large values of quenching rate constant and critical distance of energy transfer as well as fluorescence quantum yield and excited state lifetime of donor in the presence of acceptor. Moreover, these composites, which were used as an emissive layer in organic light emitting diodes, were investigated in terms of current–voltage and electroluminescence spectra

New hybridization approach of titanium organometallic: PANi thin films as room temperature gas sensors

The aim of this research was to investigate the ability of organometallic titanium-PANi hybrid materials as gas sensor at room temperature. To form the hybrid materials, commercially available polyaniline (PANi) powder were directly added into organometallic titanium sols which was synthesized using the sol gel method. The composite films were prepared via spin coating technique followed by electrode deposition for sensors fabrication. Five different organometallic titanium:PANi ratios namely 1 wt% to 5 wt% of PANi were prepared for this experiment. For gas sensing test, all samples were exposed to ethanol vapour. The sensing mode is based on the variation in the electrical conductivity due to the interaction between the gas molecules and the film. It was observed that the composite sensors required appropriate ratio to exhibit optimum sensing properties. This finding proved that the hybridization process is successful and offered much cheaper and easier method for fabrication of room temperature gas senso

Optical properties of poly(9,9’-di-n-octylfluorenyl-2.7-diyl)/amorphous SiO2 nanocomposite thin films

Identified as potential materials for optoelectronic applications, the polymer/inorganic nanocomposites are actively studied. In this work, the effect of amorphous silica nanoparticles (NPs) content on the optical properties of Poly (9,9’-di-n-octylfluorenyl- 2.7-diyl) (PFO) thin films has been investigated. Different ratios of PFO/SiO2 NPs composites have been prepared using solution blending method. Then, the blends were spin-coated onto glass substrates at 2000 rpm for 30 s and subsequently dried at room temperature. XRD and TEM were used to determine the structural properties, while UV-Vis and PL spectrophotometers were employed to investigate the optical properties of the films. XRD confirms that there was no variation on structure of both PFO and SiO2 NPs resulted from the blending process. TEM micrographs display that majority of amorphous SiO2 NPs were well coated with PFO. The absorption spectra of the composite thin films were red-shifted, indicating the increment in conjugation length of the PFO/SiO2 composite. In addition, the calculated values of the optical energy gap, the width of the energy tails and vibronic spacing of the composite films exhibited SiO2 content dependence

Pressure sensing behaviour of sodium bismuth titanate ceramics

A study to determine the microstructure and pressure sensing behaviour of Na0.45Bi0.55TiO3 (NBT) as lead-free ceramics has been conducted. NBT ceramics were prepared using the solid state reaction technique from stoichiometric mixture of Na2CO3, Bi2O3 and TiO2 powders. The mixture was sintered at three different temperatures namely 1100 oC, 1200 oC, 1300 oC for 12 hours. After sintering, the NBT powders were ground and pressed into pellet with 13 mm diameter and subsequently heated at 700 oC for 2 hours. Microstructure and morphology of the samples were determined using XRD and SEM, respectively. Customized pressure chamber using pneumatic load was employed for pressure sensing behaviour of the samples. X-ray diffraction analysis revealed that all samples consist of more than 70% of polycrystalline, rhombohedral NBT phase, with bismuth titanate, Bi2Ti2O7 (BTO) as the secondary phase. The increment in sintering temperature has resulted in the formation of higher NBT content in the sample. SEM micrographs showed that grain size and bulk density of the samples increased with the increment of sintering temperature. Pressure sensing test showed that all samples were responsive toward pressure variations only when initial voltage was applied to the ceramics. Based on density, stability and repeatability in pressure sensing behavior, NBT ceramic sintered at 1200 oC was the best ceramic with great potential as lead free pressure sensing material

Struktur dan sifat optik filem nipis nanozarah ZnO terdop Ga

Filem nipis ZnO terdop Ga (ZnO:Ga) disediakan menggunakan teknik sol-gel dan salutan berputar. Ga didopkan kepada ZnO dengan peratusan berat (wt. %) yang berbeza iaitu 0, 2, 4, 6 dan 8 wt. %. Kesan pengedopan Ga ke atas struktur dan sifat optik filem nipis ZnO dikaji. Pencirian struktur filem nipis ini dilakukan menggunakan kaedah pembelauan sinar-X (XRD), mikroskop imbasan elektron pancaran medan (FESEM) dan mikroskop daya atom (AFM). Pencirian sifat optik filem nipis pula dilakukan menggunakan spektroskopi ultraungu cahaya nampak (UV-VIS) dan fotoluminesen (PL). Ujian XRD mengesahkan kesemua sampel berstruktur wurtzit. Saiz kristalit ZnO mengecil dengan peningkatan peratusan berat Ga seterusnya mengurangkan kekasaran permukaan filem. Pengedopan Ga menunjukkan peratus transmisi cahaya pada panjang gelombang 300 - 380 nm bertambah berbanding filem nipis ZnO tanpa dop. Nilai jurang tenaga optik, Eg dan keamatan PL filem nipis ZnO meningkat apabila pengedopan Ga dilakukan. Hasil kajian ini menunjukkan saiz kristalit yang lebih kecil memberi kesan ke atas sifat optik sampel pada peratus pengedopan Ga 0-6%. Pada peratus pengedopan Ga yang lebih tinggi, kesan transformasi struktur menjadi lebih dominan dalam mempengaruhi nilai Eg

Efficient Charge Transfer Mechanism in Polyfluorene/ZnO Nanocomposite Thin Films

The optical properties and charge transfer mechanism of poly (9,9′-di-n-octylfluorenyl-2.7-diyl) (PFO)/ZnO thin films have been investigated. The ZnO nanorods (NRs) were prepared via a microwave technique. The solution blending method was used to prepare the PFO/ZnO nanocomposites. X-ray diffraction (XRD) and field emission scanning electron microscope (FE-SEM) were used to determine the structural properties, while UV-Vis and photoluminescence (PL) were employed to investigate the optical properties of the films. XRD patterns confirmed that there was no variation in the structure of both PFO and ZnO NRs due to the blending process. FE-SEM micrographs displayed that ZnO NRs were well coated by PFO in all nanocomposite films. The absorption spectra of the nanocomposite thin films exhibited a red-shift indicating the increment in conjugation length of the PFO/ZnO nanocomposite. Significant quenching in the emission intensity of PFO was observed in fluorescence spectra of the nanocomposite films. This quenching was attributed to efficient charge transfer in the PFO/ZnO nanocomposites, which was further supported by the shorter PL lifetime of PFO/ZnO than that of the PFO thin film. The continuous decline in PL intensity of these nanocomposites is attributed to homogenous dynamic quenching between PFO and ZnO NRs

Influence of TiO2 Nanoparticles on Enhancement of Optoelectronic Properties of PFO-Based Light Emitting Diode

Improvement on optoelectronic properties of poly (9,9′-di-n-octylfluorenyl-2.7-diyl)- (PFO-) based light emitting diode upon incorporation of TiO2 nanoparticles (NPs) is demonstrated. The PFO/TiO2 nanocomposites with different weight ratios between 5 and 35 wt.% were prepared using solution blending method before they were spin coated onto Indium Tin Oxide substrate. Then a thin Al layer was deposited onto the nanocomposite layer to act as top electrode. The nanocomposites were tested as emissive layer in organic light emitting diodes (OLEDs). The TiO2 NPs played the most crucial role in facilitating charge transport and electrical injection and thus improved device performance in terms of turn-on voltage, electroluminescence spectra (EL), luminance, and luminance efficiency. The best composition was OLED with 5 wt.% TiO2 NPs content having moderate surface roughness and well distribution of NPs. The device performance was reduced at higher TiO2 NPs content due to higher surface roughness and agglomeration of TiO2 NPs. This work demonstrated the importance of optimum TiO2 NPs content with uniform distribution and controlled surface roughness of the emissive layer for better device performance

Effect of ZnO addition on structural properties of ZnO-PANi/carbon black thin films

The aim of this project was to investigate the effect of ZnO addition on the structural properties of ZnO-PANi/carbon black thin films. The sol gel method was employed for the preparation of ZnO sol. The sol was dried for 24 h at 100°C and then annealed at 600°C for 5 h. XRD characterization of the ZnO powder showed the formation of wurtzite type ZnO crystals. The ZnO powder were mixed into PANi/carbon black solution which was dissolved into M-Pyrol, N-Methyl-2-Pyrrolidinone (NMP) to produce a composite solution of ZnO-PANi/carbon black. The weight ratio of ZnO were 4 wt%, 6 wt% and 8 wt%. The composite solutions were deposited onto glass substrates using a spin-coating technique to fabricate ZnO-PANi/carbon black thin films. AFM characterization showed the decreasing of average roughness from 7.98 nm to 2.23 nm with the increment of ZnO addition in PANi/carbon black films. The thickness of the films also decreased from 59.5 nm to 28.3 nm. FESEM image revealed that ZnO-PANi/carbon black thin films have changed into agglomerated surface morphology resulting in the increment of porosity of the films