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Development of optoelectronic properties of a novel graphene oxide/ copper phthalocyanine composite: Production and photoelectric characteristics of diode
(Elsevier, 2025) Gunsel, Armagan; Gunsel, Hilal; Piskin, Hasan; Bilgicli, Ahmet T.; Gunduz, Bayram; Yarasir, M. Nilufer
Novel copper (II) phthalocyanine bearing 3-chloro-4-fluorophenoxy (2) and its graphene oxide (GO)-based composites (2a-2f) were synthesized and characterized. The single crystal of the starting material compound (1) was analyzed for the first time using X-ray diffraction in this study. Phthalocyanine composites containing different percentages of graphene oxide by weight (wt.% GO) were prepared. SEM (scanning electron microscopy) results confirmed the interaction between GO and CuPc (2). In this study, the effects of concentration on the optoelectronic and conductivity properties of CuPc (2), as well as the influence of graphene oxide on the optoelectronic properties of CuPc (2) were extensively investigated. Additionally, the surface morphological properties of the phthalocyanine film were analyzed. Finally, an n-Si/CuPc (2)/Al diode was fabricated, and its photoelectric properties were investigated.
Experimental and Theoretical Investigation of the Electronic, Optical, and Structural Properties of 2-(3,5-Bistrifluoromethylphenyl)-3-(4-Methoxyphenyl)acrylonitrile for Photonic Applications
(Wiley-V C H Verlag Gmbh, 2025) Ozen, Leyla Babali; Ozen, Furkan; Gunduz, Bayram; Cin, Gunseli Turgut; Ekici, Oner
Herein, the changes in the electronic, optical, and structural properties of 2-(3,5-bistrifluoromethylphenyl)-3-(4-methoxyphenylacrylonitrile) (PAN) are investigated using both experimental and theoretical techniques. The electronic and photonic parameters of the compound are examined experimentally and theoretically in different solvents (acetone and (dimethyl sulfoxide) DMSO). The calculated FT-IR, NMR, and UV-vis spectral values are compared with density functional theory calculations, and their agreement with experimental results is evaluated. The optical parameters of the compound in acetone and DMSO, including the absorption band edge, optical bandgap, refractive index, and contrast values, are analyzed in detail. The optical bandgaps of the molecule in acetone and DMSO are found to be 3.106 and 3.088 eV, respectively. Additionally, the lower optical band edge in DMSO compared to acetone indicates that DMSO is a more suitable solvent for photonic devices requiring a lower band edge. The nonlinear optical properties of the compound, including polarizability, hyperpolarizability, and dipole moments, are examined to assess its suitability for photonic applications. Furthermore, a photonic device based on PAN is fabricated, and its electronic properties are investigated in the dark and under UV illumination at 254, 365, and 400 nm.
Influence of the Dipole Moment on the Increase in the Thermal Conductivity of Thin Films Functionalized with Azo Dye
(Amer Chemical Soc, 2024) Mikaeeli, Ameneh; Korte, Dorota; Rerek, Tomasz; Chomicki, Dariusz; Gunduz, Bayram; Derkowska-Zielinska, Beata; Pawlak, Michal
The functionalized polymers containing azobenzenes with different electron-donating and electron-withdrawing substituents in the form of a side-chain system were investigated using photothermal beam deflection spectroscopy (PBDS). The azopolymers were deposited on glass substrates using a spin-coating method with thicknesses below 450 nm. PBDS was used to determine the thermal properties of the prepared polymer samples. The topography of studied compounds was examined by atomic force microscopy (AFM). The obtained results showed the influence of the substituents in the polymer side chain on the thermal properties of studied materials. The thermal conductivity (K) extracted from PBDS measurements was found to range from 0.978 to 1.76 W m(-1) K-1. Likewise, the thermal diffusivity changed from 0.663 to 1.16 mm(2) s(-1). The thicknesses of the samples were estimated based on ellipsometric measurements. The results of these studies show that by adding different substituents to azo-based polymers, the thermal conductivity can be effectively increased (slightly less than 1 order), which leads to better heat dissipation in devices made on its basis. These results enable the precise and sensitive analysis of thermal properties across a broad range of applications.
Methoxy-substituted phenylacrylonitrile bearing an m-CF3 group: crystal structure and solvent-dependent excitonic-thermodynamic behavior
(Springer, 2026) Ozen, Leyla Babali; Ekici, Oner; Gunduz, Bayram; Ersanli, Cem Cuneyt; Cin, Gunseli Turgut; Ozen, Furkan
The structural, electronic, and optical properties of the D-pi-A chromophore 3-(4-methoxyphenyl)-2-(3-(trifluoromethyl)phenyl)acrylonitrile (MTFMAN) were comprehensively investigated using a multiscale approach combining single crystal X-ray diffraction, UV-Vis spectroscopy, and Density Functional Theory (DFT), including Time-Dependent DFT (TD-DFT) and explicit solvent cluster modeling. X-ray analysis confirmed that the compound crystallizes in a monoclinic system (space group P2(1)/n) with a unit cell volume of 1520.4(4) & Aring;(3), stabilized by dominant non-covalent interactions, specifically pipi stacking and C-HF interactions. Optical measurements demonstrated significant solvatochromism; as solvent polarity increased from acetone to DMSO, the absorption maximum shifted from 339 to 344 nm, and the experimental optical band gap decreased from 3.116 to 3.062 eV. TD-DFT calculations confirmed that the dominant Intramolecular Charge Transfer (ICT) is stabilized by the polar DMSO environment. Explicit solvent cluster modeling validated these effects, by identifying a stable C - H & ctdot;O = S interaction with a stabilization energy of -35.58 kJ/mol. Furthermore, thermodynamic properties (heat capacity, entropy, and enthalpy) were evaluated over a wide temperature range of 100-1000 K, with all data accurately fitting second-order polynomial models (R-2 > 0.999). These quantitative results highlight the tunability and thermal stability of MTFMAN for solution-processed optoelectronic applications.
Optical properties of BPP and DPP spiro-cyclotriphosphazenes: experimental and DFT insights
(Springer Int Publ Ag, 2026) Ozen, Leyla Babali; Ozkan, Gul; Kurt, Erdal; Cin, Gunseli Turgut; Gunduz, Bayram; Ozen, Furkan
Spiro-cyclotriphosphazenes such as 2,2-dichloro-4,4,6,6-bis[spiro(2',2''-dioxy-1',1''-biphenyl)]cyclotriphosphazene (DPP) and 2,2,4,4-tetrachloro-6,6-[spiro(2',2''-dioxy-1',1''-biphenyl)]cyclotriphosphazene (BPP) are well-established intermediates for functional phosphazene derivatives. However, their intrinsic optical and electronic properties have not been systematically explored under varying experimental conditions. In this work, DPP and BPP were synthesized and characterized to elucidate the correlation between structural parameters and photophysical behavior. A complementary experimental approach was employed: DPP optical properties were examined in solution as a function of molarity, while BPP properties were investigated in the solid state as a function of film thickness. This strategy enables a comparative evaluation of how intermolecular interactions and structural topology influence optical behavior. UV-Vis measurements revealed band-gap narrowing from 3.904 to 3.805 eV for BPP and from 3.921 to 3.830 eV for DPP, accompanied by red shifts. DFT calculations (B3LYP/6-31G(d,p)) reproduced the relative trends, with HOMO-LUMO gaps of 1.91 eV (BPP) and 0.92 eV (DPP); although absolute values differ from experiment, the calculations correctly predict the relative absorption onsets and tunable optical behavior. Molecular electrostatic potential (MEP) maps and conceptual DFT descriptors indicate that BPP is harder and more electrophilic, while DPP is softer and more polarizable, consistent with red-shifted absorption. These findings highlight the intrinsic optical robustness of both compounds and demonstrate that parameters such as film thickness, solution molarity, and ring topology can be used to tailor optoelectronic properties. The study establishes BPP and DPP as promising candidates for UV-blue optoelectronic devices, photodetectors, and wide-bandgap photonic materials.
Optimizing 3-MeO-BTFMAN thin films: Structural insights and photonic performance for advanced optoelectronic applications
(Elsevier, 2025) Ozen, Leyla Babali; Yakali, Gul; Ozen, Furkan; Ekici, Oner; Gunduz, Bayram; Cin, Guenseli Turgut; Aygun, Muhittin
Thin films of 2-(3,5-Bistrifluoromethylphenyl)-3-(3-Methoxyphenyl)acrylonitrile (3-MeO- BTFMAN) were prepared with different film thicknesses (8.51 mu m, 16.72 mu m, and 27.06 mu m) using the spin-coating method, with DMSO as the solvent. The photonic properties and refractive indices of the prepared 3-MeO-BTFMAN solution and films were thoroughly investigated using a combination of experimental and theoretical methods. However, as the effect of film thickness on photonic properties could not be explored using Density Functional Theory (DFT) method, this aspect was analyzed solely through experimental approaches. The molecular structure of the 3-MeO-BTFMAN compound was analyzed through a combination of theoretical calculations using the DFT method and experimental analyses involving via X-ray diffraction and spectroscopic techniques. Results showed that the optical band gap of the 3- MeO-BTFMAN film decreased from 3.268 eV to 3.199 eV with increasing film thickness, which demonstrates the impact of film thickness on photonic properties. Additionally, the refractive index of the film exhibited normal dispersion behavior. These findings suggest that the 3-MeO-BTFMAN films hold promise for applications in optoelectronic devices.
Optoelectronic Properties of a Newly Synthesized Electro-Optically Active Heterocyclic Compound Including Pyrazole, Coumarin and Acrylonitrile Groups
(Springer Heidelberg, 2025) Kurt, Adnan; Gunduz, Bayram; Onyilmaz, Mehmet; Koca, Murat
In the present work, a new molecule with high pi-bond conjugation containing the pyrazole, coumarin and acrylonitrile groups, which are important for optoelectronic technology, was synthesized by the reaction of 3-(2-oxo-2H-chromen-3-yl)-1-phenyl-1H-pyrazole-4-carbaldehyde and phenylacetonitrile in the presence of pyridine, catalytic amount of piperidine and DMF solvent. This molecule was named as 3-(3-(2-oxo-2H-chromen-3-yl)-1-phenyl-1H-pyrazol-4-yl)-2-phenylacrylonitrile (OCPAN). The spectral characterization was performed by FTIR, 1H and 13C-NMR techniques. UV-VIS measurements were carried out on a series of solutions prepared at various concentrations in DMF, across a wavelength range of 200-1000 nm. The optical and optoelectronic properties of the newly synthesized compound were thoroughly analyzed, and the effect of concentration on these properties was also investigated. Important optical and optoelectronic parameters such as absorption optical band edge, optical band gap, refractive index, incidence angle, refraction angle, contrast, optical conductance, and electrical conductance were determined. The optical band gap of the OCPAN molecule decreased from 3.202 to 3.036 eV as its concentration increased from 0.007 to 0.176 mM. These results confirm that the OCPAN molecule exhibits semiconductor characteristics.
Photophysical insights into TFHA-OP: Optimizing Optical Performance Through Solvent and Film Thickness Control
(Elsevier, 2025) Ekici, Oner; Ozen, Furkan; Ozen, Leyla Babali; Ersanli, Cem Cuneyt; Gunduz, Bayram; Cin, Gunseli Turgut
Conjugated organic semiconductors with donor-it-acceptor (D-it-A) structures are pivotal for optoelectronic applications. This study investigates the optical properties of 2-(4-trifluoromethylphenyl)-3-(4-hydroxyphenyl) acrylonitrile (TFHA-OP), focusing on solvent and film thickness effects.UV-Vis spectroscopy shows that DMSO reduces the optical band gap t o 3.107 eV, compared to acetone, while increasing film thickness further lowers the band gap to 2.965 eV at 28.7 mu m, alongside an enhanced refractive index. TD-DFT and HOMO-LUMO analysis support these findings, confirming significant solvent and thickness dependence. Importantly, this study evaluates the nonlinear optical (NLO) properties in solution for the first time, revealing that DMSO significantly boosts beta tot by 2.7-fold. These findings underscore TFHA-OP's strong light-matter interaction in thin films, positioning it as a promising candidate for efficient, low-cost, and flexible optoelectronic devices, such as photovoltaics and sensors.
Structural and photoelectrical properties of an MDMO-PPV/n-Si hybrid heterojunction photodiode for broadband detection
(Elsevier, 2026) Karaca, Abdullah; Yildiz, Dilber Esra; Hussaini, Ali Akbar; Yildirim, Murat; Gunduz, Bayram
Organic-inorganic hybrid photodiodes are attractive for low-cost, broadband photodetection, yet the role of the polymer/Si interface on power-and wavelength-dependent performance is still not fully clarified. In this study, we fabricate a simple Al/MDMO-PPV/n-Si/Al heterojunction photodiode using a solution-processed MDMO-PPV interlayer and systematically correlate its structural, optical and electrical characteristics. UV-Vis spectroscopy reveals a pronounced absorption band at 478nm, and Tauc analysis yields a direct optical band gap of 2.28 eV. XRD and SEM measurements indicate a predominantly amorphous, porous polymer film with short-range order, providing interconnected pathways for charge transport. Current-voltage measurements under light illumination from 20 to 100 mWcm(-2) show clear rectification with negligible dark current. Thermionic-emission and Cheung analyses give ideality factors of 3.0-3.5 and zero-bias barrier heights of 0.69-0.74 eV, while the photocurrent follows a power law I-ph proportional to P-1.42, evidencing trap-assisted photoconduction. The device operates over 300-1050 nm, where the responsivity (R) increases from 0.15 to about 0.42 AW(-1), the photosensitivity (K) rises to approximate to 4 - 13, and the specific detectivity (D) improves from similar to 1.1 x 10(10) to similar to 1.8 x 10(10) Jones. Time-resolved measurements at 0V bias yield rise and fall times of 0.70 s and 0.94 s, respectively. These results demonstrate that an MDMO-PPV interlayer can efficiently extend n-Si photodiodes into the visible-NIR region and provide bias-free broadband detection, offering a scalable and low-cost platform for next-generation optoelectronic and sensing applications.
Synthesis of the New 1-(7-Methoxy-1-benzofuran-2-yl)-3-(4-methylphenyl)prop-2-en-1-one and Controlling of Spectroscopic, Optical and Conductivity Properties by Concentration
(Slovensko Kemijsko Drustvo, 2022) Coskun, Demet; Coskun, Mehmet Fatih; Gunduz, Bayram
Chalcone derivatives have an important place in science due to their different applications ranging from their semiconductor properties to biological properties. In this work 1-(7-methoxy-1-benzofuran-2-yl)-3-(4-methylphenyl)prop-2-en-1-one (2) has been prepared by condensation of 1-(7-methoxy-1-benzofuran-2-yl)ethanone with 4-methylbenzaldehyde in basic medium. The chemical structure of 2 was confirmed by elemental analysis, FT-IR, H-1 NMR and C-13 NMR. UV spectroscopic characteristics, absorption band edges, optical band gaps, refractive indices, environmental behaviors and conductivity properties of 2 in solutions at different concentrations were investigated in detail. With the concentration, we examined how the spectroscopic, optical and conductivity properties of 2 have changed and can be controlled.
Synthesis, characterization of Schiff base and its metal complexes and investigation of their electronic and photonic properties
(Elsevier, 2024) Turan, Nevin; Seymen, Halil; Gunduz, Bayram; Buldurun, Kenan; Colak, Naki
A novel Schiff base (L) and its Pd(II) and Pt(II) complexes were synthesized. The Schiff base was prepared by condensation of 6-tert-butyl 3-ethyl 2-amino-4,5-dihydrothieno[2,3-c]pyridine-3,6(7H)-dicarboxylate with 2,3,4trimethoxybenzaldehyde. The ligand and its metal complexes were characterized via spectroscopic data i.e. proton and carbon NMR, electronic spectra, FT-IR, LC-MS, as well as melting point, micro analysis, magnetic measurement, molar conductance, and thermogravimetric analysis. The ligand acted as a bidentate molecule coordinating through NO heteroatoms to Pd(II) and Pt(II) metal ions. The geometric structures of Pd(II) and Pt (II) complexes were determined as square-planar. Electronic and photonics properties of metal(II) complexes were investigated under different conditions. Although the optical band gap and refractive index values of the ligand are close to the limit values of the semiconductor, it appears to be an ideal material especially for the semiconductor-insulator region of electronic and optoelectronic devices.
The light detection performance of Al/DPAVBi/n-Si heterojunction for wide-range spectrum
(Elsevier Science Sa, 2025) Kocyigit, Adem; Hussaini, Ali Akbar; Yildiz, Dilber Esra; Gunduz, Bayram; Yildirim, Murat
The 4,4 '-Bis[4-(di-p-tolylamino)styryl]biphenyl (DPAVBi) is a sky-blue fluorescent emitter and widely used in organic light emitting diodes (OLED) for improving optoelectronic behaviors. In this study, we employed DPAVBi as interfacial layer between Si and Al metal by spin coating technique to investigate its detection performance under various light power densities and across a broad spectrum from ultra-violet (UV) to near infrared (NIR). The crystallinity and surface morphology of DPAVBi layer were characterized by x-ray diffractometer (XRD) and scanning electron microscope (SEM). UV-Vis spectrometer was utilized to determine absorption behavior and band gap of DPAVBi layer. The diode and photodetector characteristics of the Al/DPAVBi/n-Si heterojunction were obtained by current voltage (I-V) and current-transient (I-t) measurements. According to thermionic emission theory, the Al/DPAVBi/n-Si heterojunction exhibited an ideality factor (n) of 4.07 and a barrier height (& Fcy;(b)) of 0.65 eV. The diode parameters were also confirmed by Cheung and Norde methods. The responsivity, photosensitivity, and specific detectivity values were also determined depending on the illumination of light power density and in the case wavelength. The Al/DPAVBi/n-Si heterojunction exhibited 0.89 A/W responsivity under sunlight. The wavelength-dependent photodetector parameters revealed that the Al/DPAVBi/n-Si heterojunction is more sensitive to light illumination in the visible region at a wavelength of 600 nm. The obtained results highlight that Al/DPAVBi/n-Si heterojunction can be employed as promising potential for optoelectronic applications in the visible range.
The light detection performance of Al/VNPB/n-Si Schottky photodetectors for a wide-range spectrum
(Elsevier, 2026) Yildiz, Dilber Esra; Manfo, Theodore Azemtsop; Hussaini, Ali Akbar; Yildirim, Murat; Gunduz, Bayram
A novel organic-inorganic Schottky photodetector incorporating a N4, N4 '-di(Naphthalen-1-yl)-N4, N4 '-bis(4-vinylphenyl)biphenyl-4,4 '-diamine (VNPB) thin film interlayer was fabricated and systematically characterized. The Al/VNPB/n-Si Schottky photodetectors were investigated using UV-Vis spectroscopy, X-ray diffraction (XRD), and scanning electron microscopy (SEM), revealing strong visible light absorption and high crystallinity. Electrical measurements under varying illumination intensities demonstrated enhanced rectification and significant photocurrent generation, attributed to thermionic emission and efficient photocarrier formation. Under solar illumination (20-100 mW/cm(2)), the device demonstrated strong photocurrent generation, high photosensitivity (22.05-80.58), responsivity up to 2.18 A/W, and detectivity values on the order of 10(10) Jones, confirming efficient low-noise photodetection. The device exhibited high photosensitivity, responsivity, and specific detectivity across a broad spectral range (351-1600 nm), with peak performance at 600 nm, where a maximum responsivity of 0.0366 A/W, an external quantum efficiency of similar to 75%, and a detectivity of 6.11 x 10(9) Jones were achieved. In addition, strong near-infrared performance was observed at 1000 nm, with a photosensitivity of 4.85 and a detectivity of 5.76 x 10(9) Jones. Compared to oxide-based photodetectors, the Al/VNPB/n-Si architecture demonstrated superior optoelectronic performance, positioning VNPB as a promising interfacial material for next-generation photodetection technologies.
The light detection performance of the Al/DCJTB/n-Si Schottky type photodetector for a wide-range spectrum
(Elsevier, 2026) Manfo, Theodore Azemtsop; Yildiz, Dilber Esra; Hussaini, Ali Akbar; Yildirim, Murat; Gunduz, Bayram
The 4-(dicyanomethylene)-2-t-butyl-6-(1,1,7,7-tetramethyljulolidyl-9-enyl)-4H-pyran (DCJTB) is a red fluorescent dye known for its high luminescence efficiency, color purity, and resistance to concentration quenching. DCJTB was applied as an interfacial layer between Si and Al via spin coating to investigate its effect on Schottky photodetector performance at various light intensities and wavelengths (UV-Vis-NIR). Structural and optical properties of the DCJTB layer were characterized using X-ray diffraction (XRD), scanning electron microscopy (SEM), and ultraviolet-visible (UV-vis) spectroscopy. Current-voltage (I-V) and current-time (I-t) measurements revealed that the Al/DCJTB/n-Si heterojunction exhibits an ideality factor (n) of 3.15 and a barrier height (Phi b) of 0.701 eV under dark conditions. With increasing illumination (20-100 mW/cm2), n varied from 3.884 to 3.077, while the barrier height increased slightly. The device achieved a responsivity (R) of 0.63 A/W and a specific detectivity of 1.63 x 1010 Jones under sunlight. The external quantum efficiency (EQE) reached 0.68 % at 550 nm, confirming high sensitivity in the green region, while performance declined beyond 700 nm. These findings demonstrate that the Al/DCJTB/n-Si heterojunction is most effective in the visible spectrum, making it promising for optoelectronic and photodetection applications.
Unveiling the temperature-dependent optoelectronic performance of acrylonitrile derivatives for organic semiconductors: A comprehensive DFT and experimental analysis
(Pergamon-Elsevier Science Ltd, 2026) Ozen, Leyla Babali; Ekici, Oner; Ozkan, Gul; Ozen, Furkan; Gunduz, Bayram; Cin, Gunseli Turgut
This study investigates the optoelectronic properties, crystal structures, and thermodynamic behaviors of two newly synthesized hydroxy-substituted phenylacrylonitrile derivatives (3a and 3b), starting from their synthesis. Experimental findings demonstrate that compound 3a exhibits superior optical semiconductor potential, particularly due to its lower band gap values. To better understand the mechanisms responsible for this superiority, the thermodynamic properties of the molecules-including heat capacity, entropy, enthalpy, and total energy-were systematically calculated using Density Functional Theory (DFT) at room temperature and over a temperature range. While the relationship between molecular dynamics and non-radiative decay is acknowledged in the literature, the quantitative impact of temperature-dependent thermodynamic parameters on the optoelectronic performance of organic semiconductors, as well as the mechanisms behind this effect, remains insufficiently explored. This research addresses this gap by demonstrating that the lower heat capacity, enthalpy, and entropy values of compound 3a, in comparison to 3b, are directly associated with reduced molecular dynamism and consequently enhanced optical efficiency. Linking electronic structure to thermodynamic rigidity reveals that reduced vibrational freedom in compound 3a extends exciton lifetimes, illuminating temperaturedependent decay pathways and highlighting its promise as a flexible optoelectronic active layer.

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