Browsing by Author "Kus, Mahmut"

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Ligand-Dependent Performance Optimization of CsPbX3/N-Si Schottky Photodiodes for Broadband Photodetection
(Springer, 2025) Varal, Nurhan Mehmet; Tok, Mutahire; Kirbiyik Kurukavak, Cisem; Durmus, Haziret; Kus, Mahmut
All-inorganic cesium lead halide perovskite nanoparticles (CsPbX3, X = Cl, Br) are promising candidates for optoelectronic devices due to their high absorption coefficients, narrow emission linewidths, and superior thermal stability compared to hybrid perovskites. In this work, Schottky photodiodes were fabricated on n-type Si substrates using CsPbBr3 and CsPbCl3 nanoparticle interlayers, both with native oleylamine/oleic acid ligands and after pyridine-based ligand exchange. Structural and morphological analyses via AFM revealed that pyridine treatment improved surface uniformity for CsPbBr3 films but induced aggregation in CsPbCl3 films. Electrical characterization using thermionic emission theory, Cheung's method, and Norde's method showed composition- and ligand-dependent variations in barrier height, series resistance, and ideality factors. Under varying illumination intensities, pyridine-treated CsPbBr3 devices (D2) exhibited over tenfold improvements in responsivity and detectivity compared to their untreated counterparts (D1), while pyridine-treated CsPbCl3 devices (D4) demonstrated high performance at low light intensities and maintained strong broadband detection from 351-1600 nm. CsPbCl3 devices with native ligands (D3) displayed unstable performance, excelling only in the long-wavelength infrared region (> 1400 nm). These results highlight the critical role of surface chemistry in tailoring perovskite-silicon photodiodes for broadband photodetection applications.
Rapid Synthesis of Highly Monodisperse AgSbS2 Nanocrystals: Unveiling Multifaceted Activities in Cancer Therapy, Antibacterial Strategies, and Antioxidant Defense
(Beilstein-Institute, 2025) Ulusu, Funda; Sarilmaz, Adem; Ulusu, Yakup; Ozel, Faruk; Kus, Mahmut
Nanocrystals (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.