Safizan Shaari
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Preferred name
Safizan Shaari
Official Name
Safizan, Shaari
Alternative Name
Shaari, Safizan
Shaari, S.
Main Affiliation
Scopus Author ID
55807708700
Researcher ID
AAR-5562-2021

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Solvent Effect on the Electrical and Structural Properties for MEH-PPV Organic Light Emitting Diodes (OLED)

2021-03-01 , Ismail N.A.N. , Safizan Shaari , Juhari N. , Norhayati Sabani , Ahmad M.F. , Zakaria N.F.

In this paper, the performance of the electrical properties (J-V) and surface roughness of MEH-PPV based organic light-emitting diodes (OLED) towards solvent effect was investigated. The MEH-PPV layer was deposited using spin coating technique at fixed spun speed of 3000 rpm. Two different solvents, toluene and chloroform (CHCl3) and mixture toluene:CHCl3 with the ratio of 4:1 and 1:4 were used to dilute MEH-PPV at fixed concentration of 5 mgml-1. Apparently, the mixture of solvent makes the surface roughness of the MEH-PPV films reduced to 0.15 nm and 3.59 nm under the ratio 4:1 and 1:4 respectively. Besides, the mixture solvents makes the value of turn on voltage was dropped to ∼7.2 V and ∼9 V respectively compared to non-mixture solvent. The combination of different solvent apparently gives an effect on the electrical and structural properties of organic light-emitting diode.

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The modelling of SiC Gate Oxide thickness based on thermal oxidation temperatures and durations for high-voltage applications

2023 , Nuralia Syahida Hashim , Banu Poobalan , Nor Farhani Zakaria , Manikandan Natarajan , Safizan Shaari

This research has shown that the oxide thickness for silicon carbide (SiC) based wide materials can be predicted using regression techniques in wet/dry nitrided or wet/dry non-nitrided thermal oxidation process conditions for high voltage applications by employing 2 different regression techniques: Polynomial and linear regression. The R-squared (R2) and Mean Absolute Percentage Error (MAPE) techniques are used to evaluate the regression models. Furthermore, this work investigates and presents a calculation of gate oxide thickness that is correlated to gate voltage ranges for high voltage applications. In this work, the thermal oxidation process environment is classified into 3 different processing conditions: conventional (dry and wet), dry nitrided (NO,N2O), and wet nitrided (HNO3 vapour). The findings from this study showed that wet oxidation combined with nitrided elements can produce thicker and better-quality gate oxide as compared to conventional dry and wet oxidation techniques. The outcome of this work clearly shows that gate oxide thickness may be derived from silicon carbide-based wide-bandgap materials utilizing linear and polynomial approaches using thermal oxidation durations at different temperatures for high-power applications. The regression models and formulations produced in this work are expected to aid the researchers in determining appropriate oxide thickness under practicable process conditions, with the exception of real thermal oxidation process conditions. Hence, the outcome of this work is expected to save the processing time, material, and cost of the power semiconductor device fabrication technology, mainly for high voltage applications.

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The structural and electrical characterization of PEDOT:PSS/MEH-PPV doped with PEIE OLED fabricated using spin coating technique

2020-01-08 , Juhari N. , Shukri N.I.A. , Norhayati Sabani , Safizan Shaari , Mohd Fairus Ahmad , Nor Farhani Zakaria

This paper investigates the performance of the uniformity and absorption spectrum of MEHPPV+PEIE thin films also the electrical properties for configuration of ITO/PEDOT: PSS/MEH+PEIE/Al. The sample used 0.5 wt % of PEDOT: PSS solution while 5 mgml-1 concentration of MEH-PPV solution was doped with four different concentrations of PEIE with values of 0.1 wt%, 0.3 wt%, 0.5 wt% and 0.7 wt% respectively. The untreated PEDOT: PSS and MEH-PPV+PEIE was deposited using spin coating technique at a fixed spun speed of 3000 rpm to obtain smooth surface roughness thin film. The root mean square (RMS) value, absorption spectrum and current density (A/cm-2) of the PEDOT: PSS and MEH-PPV+PEIE films were analyzed using Atomic Force Microscope (AFM), UV-Visible (UV-Vis) Spectrophotometer and Semiconductor Parametric Analyzer (SPA), respectively. The surface roughness of the films were linearly increased when the dopant concentration increased with the maximum RMS value of ∼4.74 nm. Besides, absorption peak wavelength also was red-shifted from 500 nm to 551 nm under an influence of PEIE dopant concentrations. However, the turn on voltage gives no significant trend when dopant concentration was increased but the emission of the light was emitted when the voltage was below 8 V. Among four different dopant concentrations of MEH-PPV+PEIE, the brighter light emission was observed at 0.3 wt% of PEIE. Apparently, the concentration of dopant solution gives a significant contribution to the performance of OLED in terms of structural, optical and electrical properties.

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Silicon Self-Switching Diode (SSD) as a Full-Wave Bridge Rectifier in 5G Networks Frequencies

2022-12-01 , Yi Liang T. , Nor Farhani Zakaria , Shahrir Rizal Kasjoo , Safizan Shaari , Muammar Mohamad Isa , Mohd Khairuddin Md Arshad , Singh A.K.

The rapid growth of wireless technology has improved the network’s technology from 4G to 5G, with sub-6 GHz being the centre of attention as the primary communication spectrum band. To effectively benefit this exclusive network, the improvement in the mm-wave detection of this range is crucial. In this work, a silicon self-switching device (SSD) based full-wave bridge rectifier was proposed as a candidate for a usable RF-DC converter in this frequency range. SSD has a similar operation to a conventional pn junction diode, but with advantages in fabrication simplicity where it does not require doping and junctions. The optimized structure of the SSD was cascaded and arranged to create a functional full-wave bridge rectifier with a quadratic relationship between the input voltage and outputs current. AC transient analysis and theoretical calculation performed on the full-wave rectifier shows an estimated cut-off frequency at ~12 GHz, with calculated responsivity and noise equivalent power of 1956.72 V/W and 2.3753 pW/Hz1/2, respectively. These results show the capability of silicon SSD to function as a full-wave bridge rectifier and is a potential candidate for RF-DC conversion in the targeted 5G frequency band and can be exploited for future energy harvesting application.

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Modification of photoanode surface structure via image analysis on organic polymer material based for dye-sensitized solar cell (DSSC) applications

2021-12 , N. Rosli , Norhayati Sabani , MF Ahmad , Mohd. Azarulsani Md. Azidin , Nurjuliana Juhari , NF Zakaria , Mohd Natashah Norizan , Safizan Shaari

In this study, the experiment on the modification of the photoanode with organic polymer material as copolymer template for dye-sensitized solar cell (DSSC) applications has been conducted. The two organic copolymer templates are polystyrene sphere (PS) and poly[2- methoxy-5(2-ethylhexyloxy)-1,4-phenylenevinylene] (MEH-PPV). The modification photoanodes were made using Dr. Blade’s method. These organic copolymer templates were added to improve the surface of the mesoporous titanium dioxide (TiO₂) layer, which is used as the main component in DSSC photoanode. The unmodified TiO₂ photoanode has poor aggregation and porosity of TiO₂. The addition of either MEH-PPV or PS sphere to the photoanode layer was found to affect the surface of mesoporous TiO₂ in terms of porosity, particle size distribution and shape. The analysis of the TiO2 modification was conducted using an image analysis processing method via a 2D scanning electron microscope (SEM) image. The image analysis processing method used was the ImageJ program. The DSSC of modified photoanode is fabricated using metal complex dye, Ruthenium (N719) dye. The data collected from the ImageJ program showed that by adding organic copolymer templates into TiO₂, the porosity of TiO₂ decreased from 45 % to 42 %. From the photovoltaic analysis obtained, the J-V characteristic is recorded with the photoanode of TiO₂ mixed with 1.00 wt% MEH-PPV gave the highest efficiency, which is 0.01 % with the following parameters – Voc = 0.43 V, Jsc = 0.17 mA/cm2 and FF = 0.20. Meanwhile, the photoanode of TiO₂ mixed with 0.50 wt% PS sphere gave the highest efficiency which is 0.08 % with the following parameters – Voc = 0.39 V, Jsc = 0.86 mA/cm2 and FF = 0.25.

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Silicon Self-Switching Diode (SSD) as a Full-Wave Bridge Rectifier in 5G networks frequencies

2022 , Tan Yi Liang , Nor Farhani Zakaria , Shahrir Rizal Kasjoo , Safizan Shaari , Muammar Mohamad Isa , Arun Kumar Singh , Mohd Khairuddin Md Arshad

The rapid growth of wireless technology has improved the network’s technology from 4G to 5G, with sub-6 GHz being the centre of attention as the primary communication spectrum band. To effectively benefit this exclusive network, the improvement in the mm-wave detection of this range is crucial. In this work, a silicon self-switching device (SSD) based full-wave bridge rectifier was proposed as a candidate for a usable RF-DC converter in this frequency range. SSD has a similar operation to a conventional pn junction diode, but with advantages in fabrication simplicity where it does not require doping and junctions. The optimized structure of the SSD was cascaded and arranged to create a functional full-wave bridge rectifier with a quadratic relationship between the input voltage and outputs current. AC transient analysis and theoretical calculation performed on the full-wave rectifier shows an estimated cut-off frequency at ~12 GHz, with calculated responsivity and noise equivalent power of 1956.72 V/W and 2.3753 pW/Hz1/2, respectively. These results show the capability of silicon SSD to function as a full-wave bridge rectifier and is a potential candidate for RF-DC conversion in the targeted 5G frequency band and can be exploited for future energy harvesting application.

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Fabrication of Strontium Titanate thin film with pre-crystallized layer via sol-gel spin coating method

2022-12 , Kelvin Voon Yan Jie , Mohd Fairus Ahmad , Muhammad Mahyiddin Ramli , Safizan Shaari , Arif Mawardi Ismail , Yusran Sulaiman

The technique of pre-crystallized layer is introduced in the strontium titanate (STO) thin film fabrication to improve the coating thickness and the crystallinity. The STO thin films were fabricated on glass substrates via the spin coating method with STO precursor solution that was synthesized through the sol-gel process. The characteristics of the thin films were analyzed through X-ray diffraction (XRD) analysis, profilometry, UV-Vis spectra analysis and scanning electron microscopy (SEM) analysis. In the present study, the samples of 20 layers and 25 layers (deposited on the pre-crystallized layer) exhibited better crystallinity as compared with the samples of 5 layers, 10 layers and 15 layers (without the pre-crystallized layer). The samples of 25 layers exhibited the highest film thickness (224 nm), highest absorbance intensity and the highest XRD peak intensity at 32, 40, 47 and 58°, which represent the planes (110), (111), (200) and (210), respectively. The pre-crystallized layer served as the mechanical support for further layer deposition.

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Optimization of MEH-PPV based single and double-layer TOLED structure by numerical simulation

2021-12 , T. Kersenan , Nor Farhani Zakaria , Safizan Shaari , Norhayati Sabani , Nurjuliana Juhari , Meor Ahmad Faris bin Meor Ahmad Tajudin , A.F.A Rahim

In this work, we simulated and characterized Poly [2-methoxy-5-(2’-ethylhexyloxy)-1, 4-phenylene vinylene] (MEH-PPV) based single and double-layer TOLED by using Silvaco ATLAS device simulator to achieve prominent values of electrical and optical properties of the device. MEH-PPV were used as the emitting layer (EML) in the single-layer, while addition of Poly [(3,4-ethylene dioxythiophene)-poly(styrene sulfonate)] (PEDOT-PSS) as the electron transport layer (ETL) were conducted in double-layer TOLED simulation. The EML and ETL thickness in both structures were varied between 10 – 150 nm, respectively, to observe and understand the underlying physics of the relation in the layer thickness to the electrical and optical characteristics. Furthermore, variation of the EML/ETL thickness ratio from 1:1 to 5:1 (with thickness in between 10 to 50 nm) had also been conducted. From this work, it is understood that the thickness of the EML layer plays the most important role in TOLED, and by balancing the carrier injections and recombination rate in appropriate EML/ETL thickness ratio, the electrical and optical properties can be improved. By optimizing the EML/ETL thickness and thickness ratio, an optimal forward current of 1.41 mA and luminescent power of 1.93e-18 W/μm has been achieved with both MEH-PPV and PEDOT-PSS layer thickness of 10 nm (1:1 ratio), respectively. The results from this work will assist the improvement of TOLED device to be implemented widely in low power and transparent electronic appliances.

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The effect of solvents on the performance of organic light-emitting diodes

2020-01-08 , Ismail N.A.N. , Safizan Shaari , Juhari N. , Norhayati Sabani , Mohd Fairus Ahmad , Zakaria N.F.

In this paper, we investigate the solvent effect on the performance of surface roughness, absorption spectrum of MEH-PPV thin films and J-V characteristics for MEH-PPV OLED device. The 5 mg emissive layer of poly [2-methoxy-5(2' -ethylhexyloxy)-1, 4-phenylenevinylene), MEH-PPV was diluted with 1ml toluene and 1 ml different mixture of solvent (80% toluene+20 % chloroform) which gives the concentration of 5 mgml-1 respectively. The surface roughness of MEH-PPV film was reduced to 0.3 nm and the red-shifted maximum peak wavelength value were obtained when mixture solvent was used. However, J-V gives higher turn on voltage ∼17 V for the device used mixture solvent compared to device prepared by toluene solvent. Apparently, the two different combination of aromatic and non-aromatic solvent significantly gives an effect on thin films properties and electrical properties of MEH-PPV OLED device.

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Temperature effects on electrical and structural properties of MEH-PPV/PEIE OLED Device

2020-06-16 , Nurul Afiqah Nor Ismail , Safizan Shaari , Mohd Fairus Ahmad , Norhayati Sabani , Nurjuliana Juhari , Nor Farhani Zakaria

This paper explores the performance of configuration ITO/MEH-PPV/PEIE/Al OLED under the variations of temperature. The MEH-PPV and MEH-PPV/PEIE thin film were deposited on ITO substrates using spin coating technique with fixed spin speed of 3000 rpm and baked at low temperature ranging from 90 °C to 180 °C, respectively. The surface roughness values for MEH-PPV and MEH-PPV/PEIE films were analysed using AFM with 5 μm ' 5 μm scanning area. The roughness of MEH-PPV thin films were reduced from 2.825 nm to 1.625 nm when temperature increased. Contrary to MEH-PPV/PEIE films where the roughness increased linearly up to 3.397 nm when the temperature increased. The maximum absorption peak spectrum obtained from UV-Visible (UV-Vis) was found at 500 nm to 510 nm when baked temperature were varied. Furthermore, the turn on voltage from J-V characteristics gives no specific pattern across different temperature and agreed with the trend of surface roughness values. The turn-on voltage at T = 150 °C gives the lowest value of 3 V. Overall, the variations of low temperature gives an effects on structural and electrical properties of this OLED configuration.

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