Browsing by Author "Hussaini, Ali Akbar"

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Citation - WoS: 13
Citation - Scopus: 13
Electrical Behaviors of the Co- and Ni-Based Poms Interlayered Schottky Photodetector Devices
(Wiley, 2022) Yıldırım, Murat; Kocyigit, Adem; Torlak, Yasemin; Yenel, Esma; Hussaini, Ali Akbar; Kuş, Mahmut
Polyoxometalates (POMs) are attractive materials for various applications such as energy storage, catalysis and medicine. Here, Co and Ni-based POMs are chemically synthesized and characterized by X-ray diffractometer (XRD) and Fourier transform infrared spectroscopies (FT-IR) for structural characterization. While the morphological behaviors are analyzed by scanning electron microscopy (SEM), transmission electron microscopy (TEM) and atomic force microscopy (AFM), the optical properties are investigated by UV-Vis spectrometer. Electrochemical characterizations are carried out by cyclic voltammetry to determine oxidation levels of the metal centers in the POMs. The CoPOM and NiPOM are inserted in between the Al metal and p-Si semiconductor to obtain Al/CoPOM/p-Si and Al/NiPOM/p-Si Schottky-type photodetector devices. Current-voltage (I-V) and current-transient (I-t) measurements are employed to understand the electrical properties of the Al/CoPOM/p-Si and Al/NiPOM/p-Si devices under dark and various light power intensities. The devices exhibit phototransistor like I-V characteristics in forward biases due to having POMs active layers. Various device parameters are extracted from the I-V measurements and discussed in details. I-t measurements are performed to determine various detector parameters such as responsivity and specific detectivity values for under 2 V and zero biases. The Al/CoPOM/p-Si and Al/NiPOM/p-Si Schottky-type photodetector devices can be employed in optoelectronic applications.
Citation - WoS: 5
Citation - Scopus: 4
Investigation and Calculation of Electrical Performance of Lead-Free Agbii4 Perovskite Based Schottky Photodiode Using Machine Learning
(Springer, 2025) Unver, Emre; Toprak, Ahmet; Hussaini, Ali Akbar; Kus, Mahmut; Yildirim, Murat
Lead-free nanoparticles gain importance due to their environmentally clean and reliable production processes in optoelectronics. In this study, we synthesized AgBiI4 lead-free perovskite material and used it as an interlayer to obtain a Schottky photodiode structure. Optical, morphological, and structural properties were investigated via UV-Vis, SEM, SEM-EDS, AFM, and XRD. The crystal structure was confirmed by X-ray diffraction (XRD) results. The results obtained from the UV-Visible spectrophotometer clearly showed the peaks of the crystal structure at 566.94 nm. The band gap calculated from UV-Vis results was 1.91 eV for AgBiI4 perovskite crystals. We used AgBiI4 structures as interlayers between n-type Si and Al to obtain a photodiode heterostructure and investigate their structural sensing performance using current-voltage and current-transient measurements. Ideality factor and barrier height values were calculated using machine learning. Lead-free perovskite structures recorded excellent photodetector properties, reaching 2.636 A/W responsivity and 1.30 x 1011 Jones detectivity.
Citation - WoS: 5
Citation - Scopus: 6
Self-Powered Narrowband Near-Infrared Photodetector Based on Polyoxometalate Compound
(Elsevier, 2025) Hussaini, Ali Akbar; Torlak, Yasemin; Buyukcelebi, Sumeyra; Kus, Mahmut; Yildirim, Murat
Narrowband photodetectors are employed in optical communication, where designated wavelengths are used to transmit data, and in environmental sensing to identify specific gases that absorb distinct wavelengths of light. In this study, we developed a novel polyoxometalate compound for application as a near-infrared (NIR) photodetector. Li6 [alpha-P2W18O62]-.28H2O compound was synthesized successfully and was characterized using 31P NMR, FT-IR, UV-Vis, C-V, SEM, TEM, and AFM. We used Li6 [alpha-P2W18O62]-.28H2O compound as interlayer in Schottky type photodetector structure. Photodiode and photodetector measurements were performed under various solar intensities (20, 40, 60, 80, and 100 mW), ultraviolet, visible, and near-infrared wavelengths ranging from 351 to 1600 nm. Notably, the device exhibited an excellent responsivity, external quantum efficiency, and detectivity under near-infrared wavelengths. It showed 64.17 mA/W responsivity, 4.34 x 1010 Jones detectivity and 7.96 % external quantum efficiency at 1000 nm and 0 bias voltage. Moreover, the device demonstrated 4.736 A/W responsivity and 8.57 x 1011 Jones detectivity under solar light. Furthermore, this research introduces a novel compound for developing narrowband photodetectors utilizing polyoxometalate.
Self-Powered Polyaniline/Si NIR Photodetectors for Waste Classification: Fabrication, Optimization, and Application
(American Chemical Society, 2025) Hussaini, Ali Akbar; Yilmaz, Kurtulus; Karaman, Mustafa; Yildirim, Murat
Rapid rise in the population and urbanization has led to increased waste generation, creating significant challenges for efficient waste management. Although recycling remains effective, manual sorting of diverse materials limits the scalability. In this study, we report the fabrication and optimization of polyaniline (PANI) interlayer-based photodetectors with varying film thicknesses by using plasma-enhanced chemical vapor deposition (PECVD). PANI films were characterized via UV-vis spectroscopy, FTIR, XPS, and AFM. Devices were tested under varying solar light intensities and a broad wavelength range (351-1600 nm). The photodetector with a 200 nm PANI layer exhibited the best performance, achieving a responsivity of 1.013 A/W, detectivity of 1.34 x 1011 Jones, and EQE of 114.2% under self-powered operation. We propose the use of this device for waste classification, shifting from conventional reflected NIR signal analysis to examining transmitted near-infrared (NIR) wavelengths through waste samples. Our results show that photocurrent, responsivity, and EQE from the PANI/n-Si heterojunction can reliably distinguish material types. This work demonstrates the potential of self-powered NIR photodetectors to enable automated, scalable, and efficient waste classification systems.
Citation - WoS: 10
Citation - Scopus: 11
Vapor Phase Polymerization of Pedot on Ito/Glass Surfaces for Nonenzymatic Detection of Dopamine
(Elsevier Science Sa, 2024) Yılmaz, Kurtuluş; Hussaini, Ali Akbar; Yıldırım, Murat; Karaman, Mustafa
This study demonstrates the deposition of poly(3,4-ethylenedioxythiophene) (PEDOT) as an electrically conductive polymer on the ITO-coated glass surfaces for the production of a non-enzymatic electrochemical sensor to detect dopamine. For this purpose, thin films of PEDOT were synthesized using vapor phase polymerization (VPP) from the corresponding monomer 3,4-ethylenedioxythiophene, in which iron(III)chloride was used as the oxidant. Films were deposited at different substrate temperatures, where the temperature dependence of doping and conjugation levels were studied using FTIR and XPS analyses. The highest doping and conjugation levels, as well as the highest film thickness (380 nm) was observed for the film deposited at 40 degrees C, which represented the highest conductivity of 111 S/cm. Significant differences were observed between the electrochemical responses of ITO/glass and PEDOT/ITO electrodes. Amperometric measurements indicated a limit of detection value of 2.02 mu M for dopamine using as-synthesized PEDOT/ITO electrode.