Rafizah Rahamathullah
Thumbnail Image
Preferred name
Rafizah Rahamathullah
Official Name
Rafizah, Rahamathullah
Alternative Name
Rahamathulla, Rafizah
Rahamathullah, R.
Main Affiliation
Scopus Author ID
55764144700
Researcher ID
DMZ-6313-2022

Research Output
Now showing 1 - 6 of 6
  • Publication
    Exploring ethynyl-based chalcones as green semiconductor materials for optical limiting interests
    ( 2024)
    Wan M. Khairul
    ;
    Fatimah Hashim
    ;
    Rafizah Rahamathullah
    ;
    Mas Mohammed
    ;
    Siti Aisyah Razali
    ;
    Syed Ahmad Tajudin Tuan Johari
    ;
    Suha Azizan
  • Publication
    Contribution of stilbene-imine additives on the structural, ionic conductivity performance and theoretical evaluation on CMC-based biopolymer electrolytes
    (Elsevier, 2020)
    Rafizah Rahamathullah
    ;
    Wan M. Khairul
    ;
    M.I.N Isa
    New solid biopolymer electrolytes (SBEs) were prepared by integrating stilbene-imine derivatives bearing vinylene (–CH[dbnd]CH–) and azomethine (–CH[dbnd]N–) as additives in carboxymethyl cellulose (CMC) based electrolyte. The investigation on their spectroscopic and theoretical assessments were conducted to alter the energy level in improving the structural and ionic conductivity performance. The simulated results from frontier molecular orbitals (FMO) and Mulliken-charge analysis revealed that -CF3 and -NO2 substituents significantly reduce the HOMO-LUMO gap up to 0.68 eV. The highest ionic conductivity of SBEs achieved at ambient temperature was ∼8 × 10−3 Scm-1 upon the addition of additive, obeying an Arrhenius model with reciprocal of temperature (303 K–373 K). The coordination interaction of C–O bond and CH[dbnd]N band facilitated the dissociation of more cation (H+) of NH4Cl which permits alternative route for H+ to hop into coordinating site in CMC. The outcomes are ideal in the development of electrochemical devices.
  • Publication
    Chitosan based solid electrolyte doped with new azo-azomethine additive for electric double-layer capacitor (EDLCs)
    (Elsevier Ltd, 2025-06-10)
    Tuan Siti Fatimah Tuan Mohd Pauzi
    ;
    Rafizah Rahamathullah
    ;
    M.N. Hafiza
    ;
    Qian Yee Ang
    ;
    Wan M. Khairul
    ;
    Artiqah Khairudin
    ;
    M.I. Rosli
    ;
    Fatin Saiha Omar
    Biopolymer-based solid electrolytes are gaining attention for their potential in electric double-layer capacitors (EDLCs). However, their practical application is limited by drawbacks such as low electrical performance and increased corrosive reactivity due to excessive amount of plasticizers. This present study investigates the effect of an azo-azomethine (AI) additive featuring hybrid (-N=N-) and (-CH=N-) groups, incorporated into a chitosan biopolymer matrix as a novel electrolyte for enhancing EDLC performance. Simulated results of the molecular electrostatic potential (MEP) and frontier molecular orbitals (FMO) suggest that the nitrogen (N) and oxygen (O) atoms from the azo and alkoxy substituents modulate the energy level of AI by reducing the HOMO-LUMO gap to 2.17 eV. The interaction between AI additive and chitosan was assessed using FTIR and powder-XRD analyses. The ionic conductivity of the prepared SBEs also increased by eight orders of magnitude from 7.38 × 10−10 S/cm to 1.27 × 10−2 S/cm with the contribution of 8 wt% of the additive. The EDLC cell was constructed by placing the prepared SBE within carbon-based electrodes, resulting in a specific capacitance 2.05 × 10−5 F/g. Thus, these findings demonstrate promising potential for electrochemical device applications.
  • Publication
    The experimental and DFT approaches on electronic, thermal and conductivity properties of non-linear optical bearing fused aromatic chalcones towards prospective OLEDs
    (Elsevier, 2025-01)
    Wan M. Khairul
    ;
    Anisatul Aqidah Tagiling
    ;
    Ain Qarina Muzaman
    ;
    Rafizah Rahamathullah
    ;
    Mas Mohammed
    ;
    Syaharil Saidin
    ;
    Suhana Arshad
    ;
    Ibrahim Abdul Razak
    ;
    Fazira Ilyana Abdul Razak
    ;
    Suhaila Sapari
    New derivatives of push-pull chalcone was successfully synthesized to demonstrate as NLO active on the impact of organic light emitting diode (OLED) materials. A total of three fused-aromatic chalcones (AA, AB, AC) with different substituents have been characterized through TGA, Z-scan analysis, 1H & 13C NMR, IR and UV–Vis. All the targeted compounds are nonlinear refraction (NLR) active with the range of χ(3) (∼ × 10–6 esu). AC reveals the highest value of first order hyperpolarizability (βtot) at 528.08 × 10–30 esu upon the substitution of strong electron acceptor. Theoretical investigation was performed by employing the theory of B3LYP/6–31 G (d,p) level via density functional theory (DFT) to optimize the geometries, molecular electrostatic potential (MEP) and frontier molecular orbitals (FMO). The predicted electronic properties of the molecule are supported by the experimental results, confirming the theoretical conclusions. The examination of its potential as emissive layer in OLED application was constructed on ITO substrate for electroluminescence behaviour evaluation under various direct current (DC) voltages supply. The preliminary outcomes reveal that these simple chalcone derivatives are capable of being utilised in any optoelectronic application.
  • Publication
    Deciphering ethynyl single crystal for NLO applications: Synergistic studies on the structural, Hirshfeld surface, photophysical and DFT assessment
    ( 2024)
    Wan M. Khairul
    ;
    Mas Mohammed
    ;
    Rafizah Rahamathullah
    ;
    Muhamad Fikri Zaini
    ;
    Suhana Arshad
    ;
    Abdul Razak Ibrahim
    ;
    Fazira Ilyana Abdul Razak
    ;
    Suhaila Sapari
      29  4
  • Publication
    Fused aromatic disubstituted azomethine as organic additives in NH4SCN doped CMC based electrolyte film
    (AIP Publishing, 2023)
    Rafizah Rahamathullah
    ;
    Jia Kai Low
    ;
    Wan M. Khairul
    ;
    Rozana Aina Maulat Osman
    ;
    Mohd Ikmar Nizam Mohamad Isa
    The remarkable progress of organic dye based on donor-Ï€-acceptor concepts has been extensively studied to enhance carrier mobility, electrical performance and can perform function at an optimum level in advanced electrochemical energy devices. In this study, new organic additive for solid polymer electrolyte (SPE) has been successfully synthesized by incorporating fused aromatic azomethine (-CH=N-) dye in carboxy methylcellulose (CMC) with ammonium thiocyanate (NH4SCN) based electrolyte. Assessment of the synthesized additive has been physico-chemically characterized via Fourier transform infrared (FT-IR), UV-visible (UV-vis), 1D Nuclear Magnetic Resonance (NMR) and thermogravimetric (TGA) analysis. Besides, DFT calculation revealed that the value of HOMO-LUMO gap exhibits semiconductor properties with the activation energy of 3.135 eV. The investigation of their capability as organic additive SPE has been discovered by incorporating CMC-NH4Cl via solution-casting technique. The structural analysis was conducted to study the effect of the atomic structure in correlation towards ionic and conductivity of newly develop SPE. The ionic conductivity of SPEs system has been measured using Impedance Spectroscopy with various weight percentage (wt%) of additive. The highest conductivity of SPEs at 303K was approximately ~10-3 Scm-1 at 0.6 wt%. As a result, the incorporation of fused aromatic azomethine into the SPE has a great potential to be used for electrochemical device application.
      6  19