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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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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Photoluminescence measurement of triplet sensitizer-emitter solution using a customized 3D-printed sample holder

2024-06 , Kelvin Voon Yan Jie , Safizan Shaari , Mohd Fairus Ahmad , Nor Farhani Zakaria , Norhayati Sabani

This study explores the photoluminescence (PL) measurement of triplet sensitizer-emitter (TSE) solutions using a custom 3D-printed sample holder, within the context of triplet-triplet annihilation based molecular photon upconversion (TTA-UC) systems targeting the Vis-to-UV spectral region. TTA-UC converts low-energy visible photons to higher-energy ultraviolet (UV) photons, holding promise for solar energy harvesting and photonics applications. Two TSE couples, 4CzIPN/TP and 4CzIPN/QP, were investigated, and their upconverted fluorescence spectra showed peaks at 344 nm and 354 nm / 370 nm, respectively, confirming efficient upconversion capabilities. The 3D-printed sample holder facilitated reproducible PL measurements, enabling the calculation of quantum yields (ΦUC). The 4CzIPN/TP and 4CzIPN/QP couples exhibited low quantum yields (0.028% and 0.043%, respectively), suggesting the need for improved deoxygenation methods to enhance the triplet-triplet annihilation process and overall quantum efficiency. Despite modest yields, successful UV upconverted fluorescence observation underscores the feasibility of the Vis-to-UV TTA-UC system. This study provides insights into TTA-UC optimization and demonstrates the utility of the 3D-printed sample holder for affordable and precise PL measurements, paving the way for future advancements in photonics and solar energy applications.

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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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Numerical simulation and characterization of silicon based OR logic gate operation using self-switching device

2021-12 , Y.X. Goh , Nor Farhani Zakaria , Y. L. Tan , Shahrir Rizal Kasjoo , Safizan Shaari , Muammar Mohamad Isa , A. K. Singh

Logic gates are the main components inside the integrated circuit used for almost every technological application. Nowadays, in order to enhance the performance of the smart device, while targeting in cut down of the fabrication cost and achieve low power consumption, lithography-based VLSI design technology on silicon are still being widely applied. Hence, an OR gate structure, a silicon based self-switching device (SSD) is introduced and investigated in this project. Such device is believed capable to act as an alternative for a low-powered logic gate application, suitable for CMOS devices. The SSD has an advantage in term of simplicity in fabrication process with a very low threshold voltage. Since SSD characteristics is similar to a conventional diode characteristic, the gate is designed in ATLAS Silvaco device simulator based on a diode logic to perform OR logic function after a validation of the physical and materials parameters. The electrical characterization and structural analysis were also done to observe the electrical performance and physical condition in the device. The simulated design showed a good OR logic output response with the inputs, and acceptable output ranged from around 4.5 to 4.8 V with 5 V HIGH inputs. The results from this OR gate characterization may assist in developing the logic gate for device integration and may act as a reference for future complex integrated circuit design.

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Numerical Simulation and Parameters Variation of Silicon Based Self-Switching Diode (SSD) and the Effect to the Physical and Electrical Properties

2020-12-14 , Tan Y.L. , Zakaria N.F. , Shahrir Rizal Kasjoo , Safizan Shaari , Muammar Mohamad Isa , Mohd Khairuddin Md Arshad , Rahim A.F.A.

Investigation of SOI based self-switching diode (SSD) by numerical simulation for RF -DC harvesting application is presented. The rectification performance of the SSD is based on the curvature coefficient, ? and current responsivity, ß which are closely related to the I-V characteristic of a non-linear device. In this work, the structural parameters are varied to observe the electrical and physical characteristics with the aid of ATLAS Silvaco simulation tools. The rectification performance in each variation is then compared, with the highest value of ? and ß observed at 25.20 V and 12.60 V, respectively. By identifying and understanding these control factors and their effects, distinctive variations of the structural parameters by using a more deliberate optimization method can be proposed for further improvement on the rectification performance.

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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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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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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 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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Hybrid Statistical and Numerical Analysis in Structural Optimization of Silicon-Based RF Detector in 5G Network

2022-02-01 , Yi Liang T. , Nor Farhani Zakaria , Shahrir Rizal Kasjoo , Safizan Shaari , Muammar Mohamad Isa , Mohd Khairuddin Md Arshad , Singh A.K. , Sobri S.A.

In this study, a hybrid statistical analysis (Taguchi method supported by analysis of variance (ANOVA) and regression analysis) and numerical analysis (utilizing a Silvaco device simulator) was implemented to optimize the structural parameters of silicon-on-insulator (SOI)-based self-switching diodes (SSDs) to achieve a high responsivity value as a radio frequency (RF) detector. Statistical calculation was applied to study the relationship between the control factors and the output performance of an RF detector in terms of the peak curvature coefficient value and its corresponding bias voltage. Subsequently, a series of numerical simulations were performed based on Taguchi’s experimental design. The optimization results indicated an optimized curvature coefficient and voltage peak of 26.4260 V−1 and 0.05 V, respectively. The alternating current transient analysis from 3 to 10 GHz showed the highest mean current at 5 GHz and a cut-off frequency of approximately 6.50 GHz, indicating a prominent ability to function as an RF detector at 5G related frequencies.

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