This work investigated the interaction between a 4-sulfocalix[4]arene (SC4) as the host molecule and para-aminobenzoic acid (PABA) as the guest molecule, driven by the outstanding properties of both SC4 and PABA for the development of a PABA nanosensor. PABA drugs are used in medical and pharmaceutical fields, but their potential carcinogenicity restricts their application. SC4 was chosen as the host molecule role because of its water-soluble property, contributing to its remarkable quality as a nanosensor and drug carrier. In this work, PABA was aimed to be detected. Based on an ultraviolet–visible spectroscopy (UV–Vis) study, the SC4 and SC4-PABA liquid samples were characterised. Tauc plot was applied to determine the band gap value. Besides, density functional theory (DFT), a first principle study of the sensing of PABA by SC4 was conducted using the Quantum ESPRESSO (QE) program. The band gap, density of state (DOS), and binding energy of the optimised novel SC4-PABA host–guest complexes were calculated. By comparing the absorbance and band gap of the host molecule to those of the host–guest complex, the reactivity of the host and guest molecules was indicated by the rise in absorbance and the decrease in band gap. Absorbance obtained based on Beer–Lambert law showed the formation of SC4-PABA complexes with the direct allowed transition. Furthermore, the complexes' negative binding energy showed their stability and favourable reactions. The optimum formation of complexes by SC4 and PABA was proven at the host–guest ratio of 1:1. Applying ultrasoft pseudopotential in the band gap calculation was more precise than applying norm-conserving pseudopotential. Both the computational and experimental studies proved the detection of PABA by SC4. The study's findings suggested the role of SC4 as a promising nanosensor for PABA drugs, which can be utilised in the future development of drug sensors.

As drug carriers, calixarenes are often investigated and employed in numerous sectors as host molecules. The use of calixarenes in drug delivery systems is a relatively new notion, despite the fact that countless studies have been conducted on calixarenes and their various applications. It is worthwhile to research the computational investigation of the host-guest interaction between calixarenes and para-aminobenzoic acid (PABA) in terms of their binding energy and band gap. The first principles study of PABA sensing by calix [4] arene (C4) and calix [6] arene (C6) based on density functional theory (DFT) was carried out in this study using Quantum ESPRESSO software. By using the computational method, the binding energy, as well as the band gap of C4, C6, PABA, and the novel complexes, C4-PABA, and C6-PABA, were calculated. Different interaction distances were used in the formation of complexes. Our results demonstrate the reduction of the band gap for both complexes. Furthermore, the calculated binding energy shows the promising stability of the complexes. This demonstrates the sensing ability of calixarenes towards PABA and the potential anti-cancer properties of calixarene-PABA in sunscreens.

Calixarenes, being well-known macrocyclic structures, have attracted considerable interest in the field of nanosensors due to their diverse advantages. 4-Aminobenzoic acid (PABA) was aimed to be detected by both calix[4]arene (C4) and calix[6]arene (C6) in this host-guest investigation. This study investigated the development of C4-PABA and C6-PABA complexes using the Lang-muir-Schaefer (LS) method and first-principles density functional theory (DFT). All of the LS films formed were characterised by field emission scanning electron microscopy (FESEM), energy dispersive X-ray (EDX), carbon, hydrogen, nitrogen, oxygen elemental analyser (CHNS), ultraviolet-visible spectroscopy (UV-Vis), and Fourier-transform infrared spectroscopy (FTIR). Additionally, this work applied DFT to compute the binding energy and band gap. Morphological and elemental analysis based on the conducted characterisations indicated the incorporation of PABA via lower rims into both C4 and C6. The computed binding energy and band gap validated the experiment's findings that promising reactivity existed between calixarenes and PABA with the formation of stable complexes. The sensing of PABA by both C4 and C6 was proven. In the near future, the outcomes of this research can be applied to drug delivery systems for pharmaceutical and medical purposes.

Calixarenes as the macrocyclic structures have been frequently explored and utilised in a variety of industries. The concept of using calixarenes in drug delivery systems is relatively new, despite calixarenes and their numerous applications have been the subject of countless investigations. In order to build a PABA nanosensor, it is worthwhile to investigate the host-guest interaction between calix[4]arene (C4) and calix[6]arene (C6) with para-aminobenzoic acid (PABA). Using field emission scanning electron microscopy (FESEM), the morphology of ultrathin pure calixarenes and their complexes with PABA were investigated in this study. Moreover, Quantum ESPRESSO was used to conduct the density functional theory (DFT) calculations. Calculations were performed on the band gap and binding energy of C4, C6, PABA, and the new complexes C4-PABA and C6-PABA. In the construction of complexes, several interaction distances were utilised. The morphologies showed the formation of calixarene-PABA complexes. Our findings indicated a narrowing of the band gap for both complexes. In addition, the computed negative binding energy demonstrated the complexes' promising stability at the optimum host-guest ratio of 1:1. These findings denoted the superior detecting ability of calixarenes towards PABA, which might be utilised in future PABA drug sensor applications.

Cadmium telluride (CdTe) solar cells have attracted a lot of interest in recent years, attributed to their low cost and eco-friendly fabrication technique. However, the back contact is still the key issue for further improvement in device performance due to the work function difference between p-CdTe and metal contacts. In this study, the interatomic characteristics of zinc telluride (ZnTe) and Cu-doped ZnTe (ZnTe:Cu) as a back surface field (BSF) in CdTe structure is investigated using first-principles density functional theory (DFT) to overcome the Schottky barrier in CdTe solar cells. The incorporation of different doping levels of copper (Cu) in ZnTe on an atomic scale, where Zn1−xTe:Cux (x = 0, 2, 4, 6, 8, and 10) as the potential back surface field layers is investigated. The effect of doping concentration on electrical characteristics such as bandgap structure and density of states (DOS) were examined via ab initio with the Hubbard U (DFT + U) correction. The results showed an interesting gradual decrease in the bandgap energy of ZnTe from 2.24 eV to 2.10 eV, 1.98 eV, 1.92 eV, 1.88 eV, and 1.87 eV for the incremented value of Cu content of 3.13

Calixarene has attract attention especially in drug delivery and drug sensor systems due to its peculiar properties, such as functional diversity of the upper and lower rims, hydrophobic cavity, chemical stability, zero toxicity, and controlled release profile. These properties make this supramolecule an ideal candidate for drug encapsulation and sensors. P-aminobenzoic acid (PABA) is a drug in sunscreen which is widely used as a ultraviolet (UV) filter and sunburn protector to protect against solar rays. The calix[n]arene (n=4,6,8) and the host-guest interaction of calix[n]-PABA were characterized using UV–visible spectroscopy and the first-principles pseudopotential method, based on the density functional theory (DFT) and the plane-wave method as implemented into Quantum Espresso code. The DFT calculation is performed to find the estimated calix[n]arene and calix[n]arene-drug band gap. The band gap calculated using DFT has usually underestimated the insulating materials for about 30 – 50% of the experimental gap values, depending on the selected type of exchange-correlation chosen. The optical band gap value of calix[n]arene and calix[n]-PABA obtained from the UV-Visible absorption spectrum estimated using the Tauc plot are then compared with the band gap computed by DFT. The band gap narrowing shown by the complexes indicates that calix[n]arene and PABA reacted. Besides, calix[8]arene is the most promising host in this study since the calix[8]-PABA complex has the most significant binding energy. The band gaps and binding energy results will become a reference for future research in calixarene and calixarene-drug material.

The utilisation of teaching aids is one of the factors that contribute to a teacher’s attainment of effective teaching objectives and can be used by students. The purpose of this study was to 1) develop an Optical Learning Module (MPO) using Genially for Optical Topic and 2) determine the usability of the MPO created using Genially to UPSI trainee teachers. This study was designed using ADDIE Model and Behaviourism Theory. This study employs random sampling approach for 40 trainee teachers to fill the questionnaire and two UPSI Physics lecturers to validate the questionnaire and module’s usability. The instrument used was a self-created questionnaire classified into three sections: the assigments, the content of the module, and the user’s perception of the Genially based module. The percentage of agreement, mean, and standard deviation were used to analyse the result that was acquired from the questionnaires using descriptive statistics in SPSS version 25. The result showed that the module has high validity with ~97% expert agreement. The mean score for the perception of this module was 3.2988. The findings demonstrated that the module is useful as one of the tools in teaching for trainee teachers. As a result, this study shows that the utilisation of this module could contribute to improving interest in learning and assist trainee teachers, particularly in Optics.

This study aimed to develop and evaluate the usability of a Force and Motion Digital Game using Game-based learning (GBL) among physics student teachers in tertiary education. The research design of this study was developmental research based on the Instructional Design-Digital Game Based Learning model (ID-DGBL model). A group of samples of 21 student teachers were chosen using cluster sampling methods for the usability test of the developed game. A questionnaire instrument was used to collect the usability data of the developed game adapted from the user testing on game. The data collected was analysed using descriptive statistics such as percentage, mean and standard deviation. Based on the findings, the percentage of expert’s agreement for the developed game and questionnaire in the validity process were 100%, while the overall mean score for the usability of the developed game was 4.74 (SD=0.33) including the constructs of Game Usability (GU), Playability (PL), and Learning Content (LC). In the conclusion, the developed game was valid and reliable, as well as suitable to be used as game-based learning for the topic of Force and Motion. In the implication, the developed game was able to complement the conventional learning process by using the game-based learning.

This study examined the behaviors of Langmuir-Blodgett ultrathin calixarene films at the air-water interface. The Langmuir trough was used to estimate the surface pressure, surface potential, and effective dipole moment of two calixarenes, namely, calix[4]arene (THC4) and calix[8]arene (THC8). The band gap was determined using the density functional theory (DFT). The DFT simulation gave a band gap of 2.28 eV for THC4, confirming that THC4 was an insulator. The surface pressure isotherms of THC4 and THC8 yielded the expected molecular behavior from the gaseous to the solid phases. THC4 and THC8 showed a perpendicular and a parallel orientation in the air-water subphase, respectively. The ∆Vmax values of TCH4 and THC 8 were 205 mV and 141mV, respectively, and their µ﬩max values were 0.147 D and 0.088 D, respectively.

The elastic, thermodynamic and electronic properties of rhombohedra SiFe2O4 spinel-type are investigated using generalized gradient approximation (GGA) and local density approximation (LDA) approach. The results obtained confirmed the failure of bare DFT to produce the fundamental bandgap of strongly correlated systems. By incorporating the Hubbard correction term (U) on Fe 3d electron, the calculated bandgap using GGA + U was found to be 3.86 eV and this value is comparable with experimental data. The Pugh's ratio and Cauchy pressure values demonstrate the ductility nature of SiFe2O4 spinel. The temperature variation with thermodynamic properties descript the stability of SiFe2O4 spinel. The heat capacity at constant volume increases sharply with temperature and tends to the Dulong-Petit limit at high temperature. The reported value of the bandgap lies within near-ultraviolet (UV) wavelength, revealing that SiFe2O4 spinel-type material may be useful for the photo-electrochemical cell of water splitting, flat-panel displays and other optoelectronic applications.

Theoretical calculations of structural, electronic, excitonic and optical properties of N-doped Sb2S3 are studied using highly accurate first-principles approach within many-body perturbation theory (MBPT) formalism. The calculated structural parameters of undoped Sb2S3 within Wu-Cohen' s generalized gradient approximation (WC-GGA) are reasonably close to those obtained in experimental measurement. Many-body perturbation theory (MBPT) based on the G(0)W(0) approximation is used for the quasiparticle (QP) band structure. The bandgap value of 1.70 eV for the undoped Sb2S3 crystal within G(0)W(0) approximation is consistent with the experimental value of 1.70-1.80 eV. When one atom of N is introduced into Sb2S3 at Sb site, the doping effects modified the band gap from 1.70 to 1.17 eV. Also, by introducing one atom of N to S site, the band gap value reduced to 0.96 eV. Our findings confirmed that non-metal doping narrow the energy gap of semiconductor materials. The optical properties of pure and N-doped Sb2S3 are computed using G(0)W(0 )plus Bethe-Salpeter Equation (BSE) which include both electron-electron (e-e) and electron-hole (e-h) interactions. The optical gap for Sb16S24, Sb15N1S24 and Sb16S23N1 were found to be 1.54, 0.97 and 0.82 eV, respectively. The narrowing effects and strong optical absorption of N-doped Sb2S3 suggest that the investigated material is suitable for solar cells and near infrared optoelectronic applications.

PbTiO3 has emerged as a promising material for the thermoelectric application. In this study, we proposed to use density functional theory to investigate the underlying mechanism for improving the thermoelectric efficiency of ATiO3. The thermoelectric parameters of the designed surface structures have been obtained by using the Boltzmann transport equation approximation. The properties of the structure, electronic, and thermoelectricity were measured and analyzed. The surface (001) modification through the AO termination layer has increased the electrical conductivity, thus increasing the power factor. On the other hand, increasing the Seebeck coefficient, which is aided by declining thermal conductivity, which is aided by low thermopower, improves the figure of merit. It is shown that the thermoelectric performance of surface (001) SnTiO3 is higher as compared to PbTiO3 making it interesting towards lead-free materials in thin-film application.

Direct conversion of waste heat to electrical energy could address present energy challenges. Bi2Se3 is one of few thermoelectric materials known to operate at room temperature. Comprehensive analysis using density functional theory was conducted to explore the effect of nickel doping on structural, electronic, and thermoelectric properties of Bi2Se3. Local density approximation (LDA) was used with an addition of spin-orbit coupling (SOC) and van der Waals interaction scheme consideration. Analysis of the effect of SOC was elaborated. It was found that nickel has changed the crystal structure of Bi2Se3. Nickel has also changed band structure and density of state that alter the thermoelectric performance. The decreased band gap has decreased the thermopower. However, it gives advantages to the improvement of electrical conductivity. Higher electrical conductivity has risen thermal conductivity. Despite the decreased thermopower and increased thermal conductivity, the higher electrical conductivity has improved the overall thermoelectric performance of Bi2Se3 when nickel is introduced.

Good thermoelectric performance is being sought to face major problems related to energy, especially in the concern of the usage of energy on environmental impact. In this work, we investigate the underlying mechanism to enhance the thermoelectric performance of bismuth selenide (Bi 2 Se 3 ) by employing density functional theory (DFT) followed by the Boltzmann transport equation under relaxation time approximation. The structural, electronic, and thermoelectric properties were calculated and analyzed. From the analysis of combined results of thermoelectric properties and electronic properties as the function of the Fermi level, we found that the power factor of Bi 2 Se 3 is improved by increasing electrical conductivity that contributed by the large density of states and light effective mass of charge carriers. The figure of merit, on the other hand, is enhanced by increasing Seebeck coefficient that contributed by heavy effective mass and decreasing thermal conductivity that contributed by low density of states. We also found that both power factor and figure of merit can be improved through n-type doping at 300 K and p-type doping at higher temperature (400 K and 500 K).

First-principles quantum mechanical computational methods are significant tools to understand the details of crystal structures which might be difficult through experimentation. In this paper, we have presented the electronic and optical properties of the thin film structure of Sb2S3 in (001) orientation. Density functional theory based approaches are employed to determine the band structure, density of states (DOS), dielectric function and other optical parameters. Here, the investigations have been performed by full-potential linearized augmented plane-wave method (FP-LAPW) within the WIEN2k computational code. The band structure computations are done at the level of LDA-PW, PBE-GGA, PBE-GGA with SOC and PBE-GGA with mBJ potential, whereas for optical properties only PBE-GGA with mBJ potential was applied. Our calculations revealed that similar to optical properties, Sb2S3 (001) oriented thin film had shown a reduction in the band gap energy than its counterpart bulk structure. This reduction, in the electronic and optical parameters, might be better understood in the course of quantum confinement effect for improving its performance for optoelectronics applications.

Antimony sulphide (Sb2S3) is a potential candidate for alternative material in solar cell application. The structural, electronic, and optical properties of Ni doped Sb2S3 were calculated using full potential linear augmented plane wave (FP-LAPW) based on popular density-functional theory (DFT). The equilibrium lattice parameters have been calculated using Perdew–Burke–Ernzerhof (PBE) generalized gradient approximation (PBE-GGA). The band structure and density of state for Ni-doped Sb2S3 have been determined using Tran Blaha modified Becke-Johnson (TB-mBJ) potential. Our results indicate that Ni doped Sb2S3 has lower band gap energy compare to pure-Sb2S3. The optical properties of Ni-doped Sb2S3 such as absorption coefficient, reflectivity, refractive index, energy-loss function and extinction coefficient are presented. The results demonstrate that Ni-doped Sb2S3 has higher optical absorption coefficient in the visible region than pure-Sb2S3 which is good for optoelectronic applications.

Thermoelectric materials regain attention due to its capability as a solution of the environmental crisis. Bi2Te3 is one of the most efficient thermoelectric materials known that capable to operate at room temperature. A comprehensive analysis was conducted using density functional theory (DFT) that implemented in CASTEP to perform structural optimization. WIEN2K and BoltzTraP are used to calculate electronic and thermoelectric properties respectively. Local density approximation and spin-orbit coupling (SOC) were chosen within the calculation. SOC has developed multi-valleys band and increased degeneracy on band structure which indicates the increase of electrical and thermal conductivity. The occupancy of electrons also have increased. The SOC has increased the change rate of thermopower, electrical conductivity and thermal conductivity over temperature. However, SOC has decreased thermopower and overall performance of Bi2Te3. Nevertheless, the results are consistent with the other. SOC can be used to manipulate the properties of thermoelectric material for enhancement purpose.

Direct conversion of waste heat to electrical energy could address present energy challenges. Bi2 Se3 is one of few thermoelectric materials known to operate at room temperature. Comprehensive analysis using density functional theory was conducted to explore the effect of nickel doping on structural, electronic, and thermoelectric properties of Bi2 Se3 . Local density approximation (LDA) was used with an addition of spin-orbit coupling (SOC) and van der Waals interaction scheme consideration. Analysis of the effect of SOC was elaborated. It was found that nickel has changed the crystal structure of Bi2 Se3 . Nickel has also changed band structure and density of state that alter the thermoelectric performance. The decreased band gap has decreased the thermopower. However, it gives advantages to the improvement of electrical conductivity. Higher electrical conductivity has risen thermal conductivity. Despite the decreased thermopower and increased thermal conductivity, the higher electrical conductivity has improved the overall thermoelectric performance of Bi2 Se3 when nickel is introduced.

Bi2Se3 is one of the promising materials in thermoelectric devices and very useful out of environmental concern due to its efficiency to perform at room temperature. Based on the first-principles calculation of density functional theory (DFT) by using CASTEP computer code, structural and electronic properties of Bi2Se3 were investigated. The calculation is conducted within the exchange-correlation of local density approximation (LDA) and generalized gradient approximation within the revision of Perdew-Burke-Ernzerhof (GGA-PBE) functional. It was found that the results are consistent with previous works of theoretical study with small percentage difference. LDA exchange-correlation functional method is more accurate and have a better agreement than GGA-PBE to describe the structural properties of Bi2Se3 which consist of lattice parameters. LDA functional also shown more accurate electronic structure of Bi2Se3 that consist of band structure and density of states (DOS) which consistent with most previous theoretical works with small percentage difference. This study proves the reliability of CASTEP computer code and show LDA exchange-correlation functional is more accurate in describing the nature of Bi2Se3 compared to the other functionals.

Antimony sulfide (Sb2S3) micro thin-film have been received great interest as an absorbing layer for solar cell technology. In this study, to explore its further potential, electronic and optical properties of Sb2S3 simulated nano-thin film are investigated by the first-principles approach. To do so, the highly accurate full-potential linearized augmented plane wave (FP-LAPW) method framed within density functional theory (DFT) as implemented in the WIEN2k package is employed. The films are simulated in the [0 0 1] direction using the supercell method with a vacuum along z-direction so that slab and periodic images can be treated independently. From our calculations, indirect band gap energy values of Sb2S3 for various slabs are found to be 0.568, 0.596 and 0.609 eV for 1, 2 and 4 slabs respectively. Moreover, optical properties comprising of real and imaginary parts of the complex dielectric function, absorption coefficient, refractive index are also investigated to understand the optical behavior of the obtained simulated Sb2S3 thin films. From the analysis of their optical properties, it is clearly seen that Sb2S3 thin films have good values for optical absorption parameters in the visible and ultraviolet wavelength range, showing the aptness of antimony sulphide thins films for versatile optoelectronic applications as a base material.