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

Fotoelektrod tungsten trioksida terdop nikel untuk tindak balas pembelahan air fotoelektrokimia

Tungsten trioksida (WO3) merupakan salah satu fotomangkin yang berpotensi dalam aplikasi penjanaan gas hidrogen daripada tindak balas pembelahan air. Dalam kajian ini, pelbagai komposisi filem nipis WO3 terdop nikel dihasilkan pada kaca stanum(IV) oksida terdop fluorin (FTO) dengan menggunakan asid tungstik dan nikel(II) asetat sebagai bahan pemula. Selepas disepuhlindap pada 500°C selama 30 min, sampel filem nipis ini dicirikan dengan menggunakan SEM, XRD, spektrofotometer UV-Vis serta analisis fotoelektrokimia (PEC). WO3 terdop nikel mempunyai saiz zarah yang lebih besar berbanding sampel WO3 tulen dan mempunyai struktur hablur monoklinik. Jurang tenaga WO3 terdop nikel yang dianggarkan daripada spektrum UV-Vis dengan menggunakan formula Tauc adalah lebih kecil berbanding jurang tenaga bagi WO3 tulen. Ujian aplikasi PEC di bawah sinaran lampu xenon menunjukkan kecekapan penghasilan gas hidrogen oleh filem WO3 terdop nikel yang digunakan sebagai fotoanod telah dipertingkatkan

Influence of PANi Additions on methanol sensing properties of ZnO thin films

The influence of PANI additions on methanol sensing properties of ZnO thin films at room temperature had been investigated. Commercial polyaniline powder (PANI) was mixed into 3 mL ZnO solution in five different weight percentages namely 1.25, 2.50, 3.75, 5.00 and 6.25% to obtain ZnO/PANI composite solutions. These solutions were spin coated onto glass substrate to form thin films. Microstructural studies by FESEM indicated that ZnO/PANI films showed porous structures with nanosize grains. The thickness of the film increased from 55 to 256 nm, proportionate to increment of PANI. The presence of 2 adsorption peaks at ~310 and ~610 nm in UV-Vis spectrum proved that addition of PANI has modified the adsorption peak of ZnO film. Methanol vapour detection showed that addition of PANI into ZnO dramatically improved the sensing properties of the sensor. The sensors also exhibited good repeatability and reversibility. Sensor with the amount of PANI of 3.75 wt% exhibited the highest sensitivity with response and recovery time was about 10 and 80 s, respectively. The possible sensing mechanism of the sensor was also discussed in this article

Performance assessment of double pass photovoltaic/thermal solar air collector using bifacial PV with CPC and mirror reflector under Malaysian climate

The performance of photovoltaic thermal (PV/T) type solar collectors can be optimised with the use of bifacial photovoltaic panel since it can utilise the absorbed incident solar irradiance from its front and rear surface. However, its potential is highly determined by the amount of the reflected solar irradiance onto the rear surface of the panel. In this research, we assessed the potential of a novel double pass photovoltaic/thermal (PV/T) solar air collector using semi-transparent bifacial PV panel with compound parabolic concentrator and mirror reflector in Malaysia. The use of CPC and reflector was introduced to increase the amount of reflected light and hence increasing the efficiency of the collector. A mathematical model was developed, and validated o predict the performance of the solar collector. Using the validated mathematical model, the optimum mass flow rate of the bifacial PV/T collector with CPC and mirror reflector was found at 0.0589 kg/s. At this flow rate, when operated under the hot climate of Malaysia, the temperature output of as high as 51 °C is achievable implying its potential as a preheated air to regenerate desiccant materials in solar assisted cooling system and for agriculture drying application. Also, when compared with the bifacial PV/T solar collector without the CPC, the total energy useful was found almost 40% higher

A Mini Review: Can Graphene Be a Novel Material for Perovskite Solar Cell Applications?

Abstract Perovskite solar cells (PSCs) have raised research interest in scientific community because their power conversion efficiency is comparable to that of traditional commercial solar cells (i.e., amorphous Si, GaAs, and CdTe). Apart from that, PSCs are lightweight, are flexible, and have low production costs. Recently, graphene has been used as a novel material for PSC applications due to its excellent optical, electrical, and mechanical properties. The hydrophobic nature of graphene surface can provide protection against air moisture from the surrounding medium, which can improve the lifetime of devices. Herein, we review recent developments in the use of graphene for PSC applications as a conductive electrode, carrier transporting material, and stabilizer material. By exploring the application of graphene in PSCs, a new class of strategies can be developed to improve the device performance and stability before it can be commercialized in the photovoltaic market in the near future

Tuning Photophysical Properties of Donor/Acceptor Hybrid Thin- Film via Addition of SiO₂/TiO₂ Nanocomposites

The influence of SiO2/TiO2 nanocomposites (STNCs) content on non-radiative energy transfer (Förster-type) from poly (9,9′-dioctylfluorene-2,7-diyl) (PFO) to poly [2-methoxy-5-(2-ethylhexyloxy)-1,4-phenylenevinylene] (MEH-PPV) using steady-state and time-resolved photoluminescence spectroscopies was investigated at room temperature. The improved energy transfer from PFO to MEH-PPV upon an increment of the STNCs was achieved by examining absorbance, emission (PL) and photoluminescence excitation (PLE) spectra. The shorter values of the quantum yield (φDA) and lifetime (τDA) of the PFO in the hybrid thin films compared with the pure PFO, indicating efficient energy transfer from PFO to MEH-PPV with the increment of STNCs in the hybrid. The energy transfer parameters can be tuned by increment of the STNCs in the hybrid of PFO/MEH-PPV. The Stern–Volmer value (kSV), quenching rate value (kq), Förster radius (R0), distance between the molecules of PFO and MEH-PPV (RDA), energy transfer lifetime (τET), energy transfer rate (kET), total decay rate of the donor (TDR), critical concentration (Ao), and conjugation length (Aπ) were calculated. The gradually increasing donor lifetime and decreasing acceptor lifetime, upon increasing the STNCs content, prove the increase in conjugation length and meanwhile enhance in the energy transfer

Conjugated Polymers-Based Ternary Hybrid toward Unique Photophysical Properties

The improvement of optical and optoelectronic properties of the individual poly [2-methoxy-5- (2-ethylhexyloxy)-1,4-phenylenevinylene] (MEH-PPV), poly[2-methoxy-5-(3,7-dimethyl-octyloxy)-1,4-phenylenevinylene]–End capped with Dimethyl phenyl (OC1C10–PPV–DMP), and poly (9,9′-di- n -octylfluorenyl-2,7-diyl) (F8) was revealed by blending them in ternary hybrid with optimal ratio (F8/2 wt.% MEH-PPV/2 wt.% OC1C10–PPV–DMP). All individual and optimal ternary solutions were prepared via the solution-blending method followed by depositing them onto glass and ITO substrates using spin-coating technique. The semi-crystalline phase of the ternary hybrid and the strong mixing between the conjugated polymers were evidenced by observing the X-ray diffraction patterns that related to F8 into the hybrid diffractogram. The optical and optoelectronic properties of all prepared thin films were investigated in terms of absorption and emission spectra, Commission International d′Eclairage (CIE) coordinates, and current–voltage (I-V) characterizations. Emission peaks at the entire range of visible spectrum can be revealed from the ternary hybrid of the three individual conjugated polymers, producing white emission as evidenced from the emission spectrum and CIE coordinates of the hybrid. Among all fabricated organic light-emitting diodes (OLEDs) devices, the ternary hybrid-based-OLED revealed the best performance in terms of current and turn-on voltage

Controlling the Emission Spectrum of Binary Emitting Polymer Hybrids by a Systematic Doping Strategy via Förster Resonance Energy Transfer for White Emission

Tuning the emission spectrum of both binary hybrids of poly (9,9′-di-n-octylfluorenyl-2,7-diyl) (PFO) with each poly[2-methoxy-5-(2-ethylhexyloxy)-1,4-phenylenevinylene] (MEH-PPV) and poly[2-methoxy-5-(3,7-dimethyl-octyloxy)-1,4-phenylenevinylene] end-capped with Dimethyl phenyl (MDMO-PPV–DMP) by a systematic doping strategy was achieved. Both binary hybrid thin films of PFO/MEH-PPV and PFO/MDMO-PPV–DMP with various weight ratios were prepared via solution blending method prior to spin coating onto the glass substrates. The conjugation length of the PFO was tuned upon addition of acceptors (MEH-PPV or MDMO-PPV–DMP), as proved from shifting the emission and absorption peaks of the binary hybrids toward the acceptor in addition to enhancing the acceptor emission and reducing the absorbance of the PFO. Förster resonance energy transfer (FRET) is more efficient in the binary hybrid of PFO/MDMO-PPV–DMP than in the PFO/MEH-PPV. The efficient FRET in both hybrid thin films played the major role for controlling their emission and producing white emission from optimum ratio of both binary hybrids. Moreover, the tuning of the emission color can be attributed to the cascade of energy transfer from PFO to MEH-PPV, and then to MDMO-PPV–DMP

Improving Photophysical Properties of White Emitting Ternary Conjugated Polymer Blend Thin Film via Additions of TiO2 Nanoparticles

The effect of TiO2 nanoparticles on the photophysical properties of ternary conjugated polymer (CP) blends of poly(9,9-dioctylfluorene-2,7-diyl) (PFO), poly 9,9-dioctylfluorene-alt-benzothiadiazole (F8BT) and poly(2-methoxy-5(2-ethylhexyl)-1,4 -phenylenevinylene (MEH-PPV) thin films was investigated. This ternary blend used a fixed amount of PFO as the donor with MEH-PPV and F8BT in various ratios as the acceptors. The solution-blending method and the spin-coating technique were used to prepare the blends and the thin films, respectively. Through efficient Förster Resonance Energy Transfer (FRET), the desired white emission was achieved with PFO/0.3 wt.% F8BT/0.5 wt.% MEH-PPV ternary blend thin film. Additions of nanoparticles up to 10 wt.% dramatically intensified the white emission which then dimmed at higher contents due to agglomerations. The current density–voltage characteristics of the nanocomposite thin films exhibited dependency on the content and distributions of the nanoparticles. Finally, a possible underlying mechanism for the intensification of emission is proposed