Profile URL: https://hdl.handle.net/20.500.13091/11958
Job Title:Prof. Dr.
Email Address:mkus@ktun.edu.tr
Main Affiliation:02.01. Department of Chemical Engineering
Status: Current Staff
ORCID:
0000-0002-6998-6459
0000-0002-6998-6459Scopus ID:
15829529900
15829529900YÖK Akademik: 1A43D40C7F2643BE
Google Scholar:
mAABDuwAAAAJ
mAABDuwAAAAJWeb of Science ID:
PFZ-4645-2026
PFZ-4645-2026Name Variants:
Kus, Mahmut Kus, M.
57 results
Scholarly Output Search Results
Now showing 1 - 10 of 57
Other A Novel Natural Scaffold Layer Improving Efficiency, Stability and Reproducibility of Perovskite Solar Cells(2022) Yenel, Esma; Kuş, MahmutAbstract In this study, our hypothesis was to demonstrate the usability of a natural clay structure as scaffold layer in perovskite solar cells (PSCs). Sepiolite, which is a natural and environmentally friendly clay structure, has a very high active surface area and can easily be dispersed in solvents. In addition we predicted that crystallization could easily occur on their surfaces due to their surface chemistry. In the study, we firstly used a natural clay as scaffold layer in PSCs. It is observed that, efficiency, reproducibility and stability of PSCs have been significantly improved. Improvements in efficiency have been observed to be between 30–50% depending on the type of perovskite solvent used. In addition, the surface chemistry of the sepiolite resulted in better crystallization as well as stability. Due to its high-water adsorption capability, sepiolite makes the perovskite crystal more stable by trapping the residual water molecules as well as penetrated water molecules from environment. Consequently, we demonstrated that, a natural, low-cost and environmentally friendly clay may be an alternative material which may contribute to the commercialization of PSCs.Article Perovskit Kuantum Noktaların Sentezi ve Karakterizasyonu(2024-06-08) Tok, Mütahire; Kuş, Mahmut; Kırbıyık, Kurukavak Çisem; Yurdakul, Merve; Yılmaz, TuğbahanBu çalışmada, Per-KN’lar (Perovskit Kuantum Nokta) LARP (ligand destekli yeniden çöktürme) yöntemi kullanılarak sentezlenmiştir. Bu yöntem ile perovskit kuantum noktaların sentezi; uygun miktarda PbX2 ve Cs2CO3’ın oleilamin, oktadesen ve oleik asit içinde bir süre karıştırıcı yardımıyla karıştırılarak dağıtılması daha sonra oda sıcaklığında ultrasonik çubuk yardımıyla 30 dk boyunca kuvvetli bir şekilde karıştırılmasıyla yapılmıştır. Per-KN’ lar 6500 rpm de 10 dakika boyunca santrifüjlenerek çözücüsünden ayrılmıştır. Per-KN’ ların optik analizleri UV–Vis ve fotolüminesans spektrometresi ile yapılmıştır. Per-KN’ ların yapısal karakterizasyonu için XRD tekniği kullanılmıştır. Sentezlenen Per-KN’ların optik bant aralığı enerjisi, halojenür bileşimi ayarlanarak neredeyse tüm görünür aralıkta (yaklaşık 400–700 nm) ayarlanabilmektedir. Per-KN’ların XRD desenlerinde kübik fazı doğrulayan standart veri dosyalarıyla tutarlı spesifik bölgelerde belirgin pikler görülmüştür. Sentezlenmiş olan Perovskit KN yapılarının kuantum verimleri CsPbCl3, CsPbBr3, CsPbI3 için sırasıyla %47,11; %53,48 ve %75,42 olarak hesaplanmıştır. Halojen içeriği değiştirildiğinde gözlenen renk değişiklikleri, floresan spektroskopisi ile ölçülmüş ve Per-KN’ ların PL spektrumlarının 14,2-22,7 nm bant genişlikleri ile tüm görünür spektral bölge üzerinde bant kenarı eksiton rekombinasyonuna atfedilebilecek olan ayarlanabilir emisyon bandı sergilediği görülmüştür.Article Citation - WoS: 18Citation - Scopus: 19Development of Highly Luminescent Water-Insoluble Carbon Dots by Using Calix[4]pyrrole as the Carbon Precursor and Their Potential Application in Organic Solar Cells(Amer Chemical Soc, 2022-05-24) Coşkun, Yağız; Ünlü, Fatma Yelda; Yılmaz, Tuğbahan; Türker, Yurdanur; Aydoğan, Abdullah; Kuş, Mahmut; Ünlü, Caner; Yllmaz, TuǧbahanCarbon dots (CDs) are carbon-based fluorescent nanomaterials that are of interest in different research areas due to their low cost production and low toxicity. Considering their unique photophysical properties, hydrophobic/amphiphilic CDs are powerful alternatives to metal-based quantum dots in LED and photovoltaic cell designs. On the other hand, CDs possess a considerably high amount of surface defects that give rise to two significant drawbacks: (1) causing decrease in quantum yield (QY), a crucial drawback that limits their utilization in LEDs, and (2) affecting the efficiency of charge transfer, a significant factor that limits the use of CDs in photovoltaic cells. In this study, we synthesized highly luminescent, water-insoluble, slightly amphiphilic CDs by using a macrocyclic compound, calix[4]pyrrole, for the first time in the literature. Calix[4]pyrrole-derived CDs (CP-DOTs) were highly luminescent with a QY of over 60% and size of around 4-10 nm with graphitic structure. The high quantum yield of CP-DOTs indicated that they had less amount of surface defects. Furthermore, CP-DOTs were used as an additive in the active layer of organic solar cells (OSC). The photovoltaic parameters of OSCs improved upon addition of CDs. Our results indicated that calix[4]pyrrole is an excellent carbon precursor to synthesize highly luminescent and water-insoluble carbon dots, and CDs derived from calix[4]pyrrole are excellent candidates to improve optoelectronic devices.Article Improved Efficiency and Stability of Perovskite Solar Cells Based on Clays(Springer, 2023-12-01) Yenel, E.; Dölek, G.; Bütün, B.N.; Kus, M.Halide perovskites have attracted great attention from many researchers recently, particularly for their excellent optoelectronic properties in applications such as photovoltaic solar cells. In recent years, perovskite solar cells (PSCs) have made great progress with a power conversion efficiency exceeding of 26% comparable to single-crystal silicon solar cells, but the stability issue still limits commercialization. PSCs allow the absorption of large amounts of photons compared to Si solar cells and have a thin layer. This provides a great advantage in terms of cost. Another important advantage of perovskite is its long diffusion path and high carrier mobility. The degradation of PSCs is mainly due to oxygen, moisture, light and heat caused by external environmental factors. In this study, we use natural clays instead of synthetic porous materials. The clays were selected according to their chemical structure and solvent dispersibility. Montmorillonite, laponite, halloysite and Na-bentonite were used in this research. Significant improvements were observed using clays as scaffold. The improvement in efficiencies were observed around 5% with montmorillonite, 13% with halloysite and 7% with laponite in comparison with reference cell. These results show that those clays can be alternative natural, non-toxic and low-cost materials as scaffold layer in PSCs. © 2023, The Author(s), under exclusive licence to Springer Science+Business Media, LLC, part of Springer Nature.Article Inorganic CNTS as a Potential Hole-Transport Material for Extremely Stable and Effective Perovskite Solar Cells(Pergamon-Elsevier Science Ltd, 2025-12-01) Sari, Fahriye; Ozel, Sultan Suleyman; Ozel, Faruk; Bersani, Massimo; Kus, MahmutIn view of these distinctive properties, chalcogenide materials have attracted attention in response to the growing need for sustainable energy sources, with a particular focus on the efficient utilization of solar energy. One of the principal challenges associated with PSCslies in addressing the fill factor (FF) deficit and resolving stability concerns. Band alignment and resistance at the interface further reduce the fill factor, thereby limiting device performance. This research demonstrates that Cu2NiSnS4 (CNTS) can serve as an effective hole transport material for perovskite solar cells, offering an enhanced stability. In this study, kesterite-based CNTS is utilized as a hole-selective interlayer in inverted CH3NH3PbI3 perovskite solar cells (PSCs) on ITO/CNTS substrates. CNTS was selected due to its numerous advantages, including the abundance of their constituent elements in nature, non-toxicity, cost-effectiveness, appropriate band gap and absorption coefficient for photovoltaic (PV) applications, as well as their tunable band gap properties. Deposition of CNTS onto ITO glass alters the substrate's work function, resulting in open-circuit voltages exceeding 1.0 V. Solar cells on ITO substrates without a metal oxide layer demonstrated an exceptional power conversion efficiency (PCE) of 10.6 %. This highlights the potential of PSCs for high performance with a single selective contact. Our findings reveal that these cells retain over 93 % of their initial efficiency after 720 h, demonstrating improved stability. Replacing p-type organic materials with inorganic counterparts offers a promising avenue for further research.Article Citation - WoS: 1Citation - Scopus: 1Advancing Perovskite Solar Cells: Inorganic CCTS Hole-Transporting Material for Enhanced Efficiency and Stability(Elsevier, 2025-11-01) Sari, Fahriye; Ozel, Sultan Suleyman; Sarilmaz, Adem; Ozel, Faruk; Kus, Mahmut; Ersoz, MustafaOne of the most effective methods for generating renewable energy is the efficient conversion of photons into electrical energy using environmentally sustainable materials. In recent years, the integration of chalcogenide materials, which exhibit graphene-like semiconducting properties and high charge carrier mobility, into perovskite solar cells (PSCs) has garnered significant attention for enhancing the performance, stability, and ecofriendly nature of these devices. In this study, Cu2CoSnS4 (CCTS) nanocrystals were synthesized and utilized as a fully inorganic hole transport layer (HTL) in inverted PSCs. Devices incorporating 6 vol% CCTS achieved a power conversion efficiency (PCE) of 10.07 %, and retained 93 % of their initial efficiency after 720 h under inert storage conditions, without encapsulation. This demonstrates a notable improvement in stability compared to conventional PEDOT: PSS-based devices. The optimized CCTS HTL provided better energy level alignment, reduced moisture ingress, and enhanced charge transport. These findings indicate that CCTS is a promising inorganic HTL candidate for efficient and stable PSCs.Article Citation - WoS: 5Citation - Scopus: 6Rubrene Single Crystal Solar Cells and the Effect of Crystallinity on Interfacial Recombination(Royal Soc Chemistry, 2022) Kara, Duygu Akın; Burnett, Edmund K.; Kara, Koray; Usluer, Özlem; Cherniawski, Benjamin P.; Barron, Edward J.; Briseno, Alejandro L.; Kuş, Mahmut; Akin Kara, DuyguSingle crystal studies provide a better understanding of the basic properties of organic photovoltaic devices. Therefore, in this work, rubrene single crystals with a thickness of 250 nm to 1000 nm were used to produce an inverted bilayer organic solar cell. Subsequently, polycrystalline rubrene (orthorhombic, triclinic) and amorphous bilayer solar cells of the same thickness as single crystals were studied to make comparisons across platforms. To investigate how single crystal, polycrystalline (triclinic-orthorhombic) and amorphous forms alter the charge carrier recombination mechanism at the rubrene/PCBM interface, light intensity measurements were carried out. The light intensity dependency of the J(SC), V-OC and FF parameters in organic solar cells with different forms of rubrene was determined. Monomolecular (Shockley Read Hall) recombination is observed in devices employing amorphous and polycrystalline rubrene in addition to bimolecular recombination, whereas the single crystal device is weakly affected by trap assisted SRH recombination due to reduced trap states at the donor acceptor interface. To date, the proposed work is the only systematic study examining transport and interface recombination mechanisms in organic solar cells produced by different structure forms of rubrene.Article Citation - WoS: 4Citation - Scopus: 4Aggregation-Induced Red-Shift Emission From Self-Assembled Planar Naphthalene Diimide Dye: Interlayer in a Schottky-Type Photodiode and Dft Studies(Elsevier, 2024-09-01) Karşılı, Pelin; Abourajab, Arwa; Dinleyici, Meltem; Altinisik, Sinem; Koyuncu, Sermet; Dölek, Gamze; Kus, Mahmut; Icil, HuriyeIn this study, a planar, soluble, thin film-forming and self-assembled small naphthalene diimide (3) molecule with a subtle moiety at the imide-nitrogen was synthesized, and applied for the first time in literature as an interfacial layer between Al and p-Si layers in a Schottky-type photodiode. The morphology of the compound was examined by scanning electron microscopy (SEM) and atomic force microscopy (AFM). The thin film structure and morphology affected the optical and electrical properties. The energy levels of the highest occupied molecular orbitals and lowest unoccupied molecular orbitals of 3 were calculated as -6.14 eV and -4.02 eV, corresponding to the band gap of 2.12 eV consistent with density functional theory (DFT) results. Differential scanning calorimetry (DSC) studies revealed a relatively high Tg value at 208 degrees C, indicating high-temperature applicability of the crystalline structure. The I-V measurements of Al/3/p-Si heterostructure were performed under dark and various light power intensities. The current steadily rose with each incremental 20 mW increase in light intensity. The reverse current increased almost 10-fold at 100 mW/cm2 illumination compared to dark measurement. The photodiode's responsivity, photosensitivity, and detectivity factors were elucidated. The photodiode's characteristic values, such as Io, n, phi b, and Rs, were obtained as 3.50 x 10-6 A, 8.24, 0.588 eV and 2.266 k Omega, respectively. The fabricated Schottky-type diode showed promising results for the optoelectronic field. The compound's perfect solubilities in a wide range of solvents, processability, excellent chemical and photochemical stabilities, and exciting optical, thermal and electrochemical properties make it an ideal candidate for thin film and molecular electronics applications.Article Enhanced Uptake Capacities and Isosteric Heats of Co2 and Ch4 Adsorption on Spent Coffee Ground Activated Carbons Loaded With Metal Ions(Tubitak Scientific & Technological Research Council Turkey, 2019-06-11) Kırbıyık, Çisem; Büyükbekar, Burak Zafer; Kuş, Mahmut; Ersöz, MustafaLow-cost activated carbon (AC) samples obtained from waste coffee grounds were used for CO2 and CH4 adsorption. ACs were prepared by chemical activation and carbonized at three different temperatures. AC carbonized at 800 ? C showed a relatively high surface area (582.92 m2 g ?1 ) and high adsorption capacities of 2.6 mmol g ?1 and 1.1 mmol g ?1 at 25 ? C for CO2 and CH4 , respectively. Adsorbent samples were prepared by loading of Fe 3+ metal ions onto ACs and their adsorption capacities were compared with those of nonloaded ACs. As expected, the loading of Fe 3+ metal ions increased the adsorption capacities at all temperatures and the adsorption capacity of Fe 3+ -loaded AC carbonized at 800 ? C was 3.1 mmol g ?1 for CO2 and 1.2 mmol g ?1 for CH4 at 25 ? C. The isosteric heats of adsorption were calculated at 0–35 ? C with the range of 20–35 kJ mol ?1 and 18–23 kJ mol ?1 for CO2 and CH4 , respectively. According to our findings, bio-based ACs can be used as an effective and alternative adsorbent for capturing different gas molecules.Article Rapid Synthesis of Highly Monodisperse AgSbS2 Nanocrystals: Unveiling Multifaceted Activities in Cancer Therapy, Antibacterial Strategies, and Antioxidant Defense(Beilstein-Institute, 2025-11-19) Ulusu, Funda; Sarilmaz, Adem; Ulusu, Yakup; Ozel, Faruk; Kus, MahmutNanocrystals (NCs) of silver antimony sulfide (AgSbS2) in the cubic phase were successfully synthesized using the hot-injection method. This study is the first to investigate the cytotoxic effects of these NCs on human breast adenocarcinoma (MCF-7), colon cancer cell lines (HT-29), and fibroblast cell lines (L929). Additionally, the antibacterial properties of the NCs against gram-positive (Staphylococcus aureus and Bacillus subtilis) and gram-negative (Escherichia coli) pathogenic bacteria were evaluated, along with their DPPH scavenging activities. The crystal structure of the synthesized NCs was elucidated through XRD analysis, revealing characteristic diffraction peaks corresponding to the (111), (200), (220), (311), and (222) planes of the AgSbS2 phase. TEM and SEM techniques were used to comprehensively characterize the NCs. The results showed that spherical NCs were predominantly formed, with an average diameter of approximately 32 +/- 10 nm. Cytotoxicity studies demonstrated a significant inhibitory effect of the NCs, particularly on cancer cell lines (MCF-7 and HT-29), in a dose-dependent manner over a 24 h period. These findings highlight the potential of the NCs as anticancer agents. Furthermore, the synthesized NCs demonstrated potent antibacterial properties against the tested microorganisms and notable antioxidant effects by efficiently eliminating DPPH activity. This research highlights the potential of AgSbS2 NCs as versatile agents with applications in biomedical and environmental domains, including cancer therapy, antimicrobial strategies, and free radical neutralization.
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