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Additive‐free electrophoretic deposition of graphene quantum dots thin films
摘要： The electrophoretic deposition (EPD) of graphene-based materials on transparent substrates is highly potential for many applications. Several factors can determine the yield of EPD process, such as applied voltage, deposition time, and particularly the presence of dispersion additives (stabilizers) in the suspension solution. This study presents an additive-free EPD of GQDs thin films on Indium Tin Oxide (ITO) glass substrate and studies the deposition mechanism with the variation of the applied voltage (10 – 50 V) and deposition time (5 – 25 min). It is found that due to the small size (~3.9 nm) and high content of deprotonated carboxylic groups, the GQDs form a stable dispersion (zeta potential of about –35 mV) without using additives. The GQDs thin films can be deposited onto ITO with optimal surface morphology at 30 V in 5 min (surface roughness of approximately 3.1 (±1.3) nm). In addition, as-fabricated GQDs thin films also possess some interesting physico-optical properties, such as a double-peak photoluminescence at about 417 and 439 nm, with ca. 98% visible transmittance. This low cost and eco-friendly GQDs thin film is a promising material for various applications, e.g. transparent conductors, supercapacitors, and heat conductive film in smart windows.
关键词： visible transparency,graphene quantum dots,thin film,electrophoretic deposition,additive free
更新于2025-09-19 17:13:59
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Toxic Solvent‐ and Additive‐Free Efficient All‐Polymer Solar Cells via a Simple Random Sequence Strategy in Both Donor and Acceptor Copolymer Backbones
摘要： It is extremely important to develop nontoxic solvent and additive-processed high-performance all-polymer solar cells (all-PSCs) that are suitable for printing preparation of large-scale devices. Herein, it is demonstrates that a simple random copolymerization of two acceptor monomers (benzo[1,2-c:4,5-c′]dithiophene-4,8-dione (BDD) and 5,6-difluoro-2H-benzo[d][1,2,3] triazole (FTAZ)), alternating with Si atom-containing benzo[1,2-b:4,5-b′] dithiophene donor comonomer, forms a successful approach by which to synthesize donor copolymers with excellent solubility/processability for nontoxic-solvent-processed all-PSCs. The incorporation of a higher degree of BDD in the backbone lowers the frontier energy levels, as well as redshifts, with higher absorption coefficients; however, it adversely affects solubility in a 2-methyltetrahydrofuran (MeTHF). An impressive power conversion efficiency, of about 8.0%, is achieved from PJ25 (25 mol% BDD)-based all-PSC when paired with N2200-F30 acceptor random copolymer by using MeTHF as the processing solvent without any additive. Another interesting point is that the air stability of the all-PSCs increases with increasing FTAZ content due to strong noncovalent interaction and resistance to humidity and oxidation caused by the F-atoms in FTAZ units. Not only does this study establish a structure–property–performance relationship through a series of structural, morphological, and electrical characterization techniques, but it also provides a promising and easy way to develop nontoxic-solvent-processed high-performance all-PSCs.
关键词： compatibility,nontoxic solvents,random copolymers,additive-free processing,all-polymer solar cells
更新于2025-09-11 14:15:04
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Investigating Zinc Ketoiminates as a New Class of Precursors for Solution Deposition of ZnO Thin Films
摘要： Zinc oxide (ZnO) has been recognized as one of the most promising metal oxide semiconductor material for processing low-cost thin film transistors (TFTs). Within the scope of this work, we demonstrate a simple, stabilizer free and very efficient chemical solution deposition (CSD) route to grow high quality ZnO layers. The identification of a highly soluble zinc ketoiminate precursor that undergoes hydrolysis under ambient conditions with the facile cleavage of the ligands was the key to develop a simple and straightforward process for ZnO thin films under mild process conditions. Upon heat treatment at moderate temperatures, the precursor decomposes cleanly yielding polycrystalline ZnO thin films, which was confirmed by X-ray diffraction (XRD) and scanning electron microscopy (SEM). The composition was investigated employing complementary techniques such as X-ray photoelectron spectroscopy (XPS) and Rutherford backscattering spectrometry (RBS) which revealed high purity ZnO layers. The functional properties in terms of transparency and optical band gap were determined by ultraviolet-visible (UV-Vis) spectroscopy. The transparent ZnO semiconductor thin films serve as active channel layer of thin film transistors (TFT) which was demonstrated by spin coating of the precursor. Subsequent curing in ambient air, yields a 10 nm film that is sufficient to fabricate working TFTs test structures.
关键词： Oxide Semiconductors,Additive-Free Solution Processing,Composition,Thin Film Transistors
更新于2025-09-04 15:30:14