WoS İndeksli Yayınlar Koleksiyonu
Permanent URI for this collectionhttps://hdl.handle.net/20.500.12573/394
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Article Citation - Scopus: 1N-Type Molecular Thermoelectrics Based on Solution-Doped Indenofluorene-Dimalononitrile: Simultaneous Enhancement of Doping Level and Molecular Order(Wiley, 2024-09-25) Wang, Suhao; Wei, Huan; Rillaerts, Antoine; Deneme, Ibrahim; Depriester, Michael; Manikandan, Suraj; Pisula, WojciechThe development of n-type organic thermoelectric materials, especially pi-conjugated small molecules, lags far behind their p-type counterparts, due primarily to the scarcity of efficient electron-transporting molecules and the typically low electron affinities of n-type conjugated molecules that leads to inefficient n-doping. Herein, the n-doping of two functionalized (carbonyl vs dicyanovinylene) indenofluorene-based conjugated small molecules, 2,8-bis(5-(2-octyldodecyl)thien-2-yl)indeno[1,2-b]fluorene-6,12-dione (TIFDKT) and 2,2 '-(2,8-bis(3-alkylthiophen-2-yl)indeno[1,2-b]fluorene-6,12-diylidene)dimalononitrile (TIFDMT) are demonstrated, with n-type dopant N-DMBI. While TIFDKT shows decent miscibility with N-DMBI, it can be hardly n-doped owing to its insufficiently low LUMO. On the other hand, TIFDMT, despite a poorer miscibility with N-DMBI, can be efficiently n-doped, reaching a respectable electrical conductivity of 0.16 S cm-1. Electron paramagnetic resonance measurements confirm the efficient n-doping of TIFDMT. Based on density functional theory (DFT) calculations, the LUMO frontier orbital energy of TIFDMT is much lower, and its wave function is more delocalized compared to TIFDKT. Additionally, the polarons are more delocalized in the n-doped TIFDMT. Remarkably, as indicated by the grazing-incidence wide-angle X-ray scattering (GIWAXS), the molecular order for TIFDMT thin-film is enhanced by n-doping, leading to more favorable packing with edge-on orientation and shorter pi-pi stacking distances (from 3.61 to 3.36 & Aring;). This induces more efficient charge transport in the doped state. Upon optimization, a decent thermoelectric power factor of 0.25 mu Wm-1K-2 is achieved for n-doped TIFDMT. This work reveals the effect of carbonyl vs dicyanovinylene on the n-doping efficiency, microstructure evolution upon doping and thermoelectric performance, offering a stepping stone for the future design of efficient n-type thermoelectric molecules. N-doping of two functionalized (carbonyl vs dicyanovinylene) indenofluorene-based conjugated small molecules TIFDKT and TIFDMT is investigated. Remarkably, TIFDMT with a much lower LUMO energy, can be efficiently n-doped to a respectable electrical conductivity of 0.16 S cm-1. Moreover, n-doping of TIFDMT leads to more favorable packing and shorter pi-pi stacking distances, resulting in efficient charge transport in the doped state. imageArticle Citation - WoS: 1Citation - Scopus: 1Achieving High Optical Absorption in Thin Film Photovoltaic Devices via Nanopillar Arrays and Metal Nanoparticles(Wiley-VCH Verlag GmbH, 2025-07-12) Tut, TurgutIn this study, crystalline silicon nanopillars has been employed as a hexagonal array photonic crystal structure with low optical reflection, augmented by silver metallic nanoparticles ranging from 10 to 50 nm in diameter in order to achieve high absorption in thin silicon films, a critical factor for applications in photovoltaic devices. Initially, it has been begun with an optimized structure in terms of pillar filling ratio, pillar height, and diameter, as established in the previous study. This allows to obtain a hexagonal array of nanopillars with a surface characterized by low optical reflection. To enhance the optical absorption within the bulk of the silicon thin film, the optical scattering properties of silver (Ag) metallic nanoparticles (MNPs) has been harnessed. The integration of silver metal nanoparticles into the photonic crystal hexagonal nanopillar array involved introducing a cavity into the silicon pillar. Placing Ag MNPs near the bottom of the cavity prevented the degradation of the photonic crystal's ability to maintain low reflection within the desired optical spectrum (between 400-1100 nm). Comparison between the nanopillar hexagonal array structure with Ag MNPs and the bare silicon substrate revealed a remarkable 104.76 percent increase in optical absorption for a 1-micron thick silicon bulk material. This triple hybrid structure exhibits tremendous potential in photovoltaic device applications, including solar cells and photodetectors, with the capacity to significantly enhance conversion efficiency.