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

Changes in doping state of (Tl, Pb)Sr1212 superconductors with Yb substitution at Sr site

Samples with nominal starting compositions of Tl0.5Pb0.5Sr2−yYbyCaCu2O7 (y = 0–0.6) were synthesized using conventional solid-state synthesis method. Temperature dependent electrical resistance measurements on the series showed that the normal state behavior and superconducting properties can be controlled by adjusting Yb concentration to achieve maximum critical temperature (Tc). The best superconducting behavior for the series was observed for Tl0.5Pb0.5Sr1.8Yb0.2CaCu2O7 with onset critical temperature (Tc onset) of 105 K. Results of critical temperature (Tc) measurements, microstructure investigation using scanning electron microscope (SEM) and powder X-ray diffraction (XRD) analysis are presented. The effects of Yb substitutions are discussed in terms of Tc, Tl1212 phase formation and the concept of average Cu valence

Penentuan parameter optimum bagi rawatan pengutuban elektrik ke atas seramik-piezo (BaTiO3) menggunakan sistem buatan sendiri

Kajian ini dijalankan bertujuan untuk menentukan nilai optimum bagi parameter rawatan pengutuban BaTiO3 sebagai bahan seramik-piezo dengan menggunakan sistem pengutuban DC buatan sendiri. Tiga parameter pengutuban utama yang telah dikaji adalah medan elektrik (Ep), suhu (Tp) dan masa (tp) rawatan. Fasa tunggal seramik-piezo BaTiO3 yang stabil dalam struktur hablur tetragon berjaya disediakan melalui persinteran keadaan pepejal konvensional. Pemilihan julat Ep dan Tp untuk rawatan pengutuban masing-masing adalah berdasarkan ujian awal pengukuran histeresis feroelektrik dan penentuan suhu Curie, Tc. Keputusan kajian mendapati BaTiO3 mempunyai nilai medan paksaan, Ec yang kecil (~2.42 kV/cm), pengutuban baki, Pr ~4.90 μC/cm2 dan pengutuban maksimum, Pm yang besar (~17.59 μC/cm2) dengan Tc pada 139°C. Berdasarkan julat parameter kajian, nilai pemalar piezoelektrik, d33 tertinggi ~190 pC/N diperoleh dengan magnitud medan elektrik pengutuban iaitu 1.5Ec pada suhu 60°C selama 10 min. Struktur dan morfologi BaTiO3 selepas rawatan pengutuban juga dikaji. Sistem pengutuban yang dibangunkan menyusun semula penjajaran domain secara efektif dan parameter rawatan optimum didapati setanding dengan kajian BaTiO3 lain

Photophysical properties and energy transfer mechanism in PFO/TiO2 /MEH-PPV nanocomposite thin films

Improvement in photophysical properties of poly-9,9-dioctylfluorene (PFO)/10 wt. % TiO2 nanoparticle thin film as a result of systematic additions of poly(2-methoxy-5(2-ethylhexyl)-1,4-phenylenevinylene (MEH-PPV) were investigated. The nanocomposite blends were prepared with additions of MEH-PPV up to 3.0 wt. % of the total weight. All blends were prepared using the solution blending method and subsequently spin-coated onto glass substrates. The UV-Vis absorption and photoluminescence characterizations showed the intensification of the primary-color emissions of the thin films with the Förster resonance as the primary energy transfer mechanism from PFO to MEH-PPV. Important photophysical parameters, such as the Förster radius (Ro ) excited state lifetime (τ), fluorescence quantum yield of the donor (φ), quenching constant (ksv), quenching rate constant (kq ), distance between the donor and acceptor (R), energy transfer lifetime (τET), and energy transfer rate (kET) display better values with increasing the contents of MEH-PPV by 2.5 wt. %, suggesting an ordered improvement on the photophysical properties of the thin film. Finally, a possible underlying mechanism describing the enhancement of the photophysical properties was proposed

Numerical analysis with experimental verification to predict outdoor power conversion efficiency of inverted organic solar devices

Inverted organic solar cell (IOSC) devices with different volume ratios of In₂S₃ nanoparticles have been studied under local spectral irradiances in Malaysia with respect to that of AM1.5G. The J-V curves of encapsulated IOSC devices were measured outdoor using an Ivium Potentiostat and local spectral irradiances were acquired using an AVANTES spectrometer concurrently. All of the IOSC devices experienced significant improvement in power conversion efficiency (PCE) under the both local sunny and cloudy conditions with respect to the AM 1.5G, by 22–35% and 31–65%, respectively. From spectral analysis, the area under the graph of spectral irradiance in UV–visible region is significantly higher compared to infrared region for both local sunny and cloudy conditions, by 44.6% and 55.9%, respectively, while it is only recorded as 12.9% for AM 1.5G. Last but not the least, we have successfully verified the numerical analysis to predict device performance by comparing the simulated and measured PCE values for different irradiance intensities whereby the prediction of PCE is better under sunny condition with a deviation of 3.4–10.8% compared to cloudy conditions, with deviation of 28.9–30.5%

Synergy study on charge transport dynamics in hybrid organic solar cell: photocurrent mapping and performance analysis under local spectrum

Charge transport dynamics in ZnO based inverted organic solar cell (IOSC) has been characterized with transient photocurrent spectroscopy and localised photocurrent mapping-atomic force microscopy. The value of maximum exciton generation rate was found to vary from 2.6 × 1027 m−3s−1 (Jsat = 79.7 A m−2) to 2.9 × 1027 m−3s−1 (Jsat = 90.8 A m−2) for devices with power conversion efficiency ranging from 2.03 to 2.51%. These results suggest that nanorods served as an excellent electron transporting layer that provides efficient charge transport and enhances IOSC device performance. The photovoltaic performance of OSCs with various growth times of ZnO nanorods have been analysed for a comparison between AM1.5G spectrum and local solar spectrum. The simulated PCE of all devices operating under local spectrum exhibited extensive improvement with the gain of 13.3–13.7% in which the ZnO nanorods grown at 15 min possess the highest PCE under local solar with the value of 2.82%

Silver nanowires as flexible transparent electrode: role of PVP chain length

In this project, crystalline silver nanowires (AgNWs) are successfully grown using a continuous segmented flow process. The robust relationship among the structural, electrical and optical properties of the AgNWs in the function of the polyvinylpyrrolidone (PVP) chain length is elaborated. A concise carrier transport and a density mechanism are also discussed using a localized conductive atomic force microscopy analysis. The obtained results proved that the AgNWs synthesized using PVP with a chain length of 1.3 M exhibit excellent electrical and optical properties in the form of flexible transparent film with a sheet resistance of 90% at various bending angles. These findings present an alternative approach for production of AgNWs and fabrication of a high flexible transparent electrode

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