Comprehensive Study of the Chemistry behind the Stability of Carboxylic SWCNT Dispersions in the Development of a Transparent Electrode

Abstract

Single-walled carbon nanotubes (SWCNTs) are well-known for their excellent electrical conductivity. One promising application for SWCNT-based thin films is as transparent electrodes for uncooled mid-IR detectors (MIR). In this paper, a combination of computational and experimental studies were performed to understand the chemistry behind the stability of carboxylic SWCNTs (SWCNTs-COOH) dispersions in different solvents. A computational study based on the density functional tight-binding (DFTB) method was applied to understand the interactions of COOH-functionalized carbon nanotubes with selected solvents. Attention was focused on understanding how the protonation of COOH groups influences the binding energies between SWCNTs and different solvents. Thin film electrodes were prepared by alternately depositing PEI and SWCNT-COOH on soda lime glass substrates. To prepare a stable SWCNT dispersion, different solvents were tested, such as deionized (DI) water, ethanol and acetone. The SWCNT-COOH dispersion stability was tested in different solvents. Samples were prepared to study the relationship between the number of depositions, transparency in the MIR range (2.5–5 µm) and conductivity, looking for the optimal thickness that would satisfy the application. The MIR transparency of the electrode was reduced by 20% for the thickest SWCNT layers, whereas sheet resistance values were reduced to 150–200 kΩ/sq.

Single-Walled Carbon Nanotube-Modified Gold Leaf Immunosensor for Escherichia coli Detection

“…As in our previous work, , we used a simple, low-cost LbL technique to fabricate a CNT-based biosensor. The principle of the LbL technique is based on the alternate deposition of positively and negatively charged layers to form a thin monolayer film.…”

Editorial for Special Issue: “Preparation of Nanomaterial Modified Electrode and Its Sensing Application”

“…Our Special Issue includes eleven research papers, consisting of nine articles and two reviews. These reports cover the preparation of nanomaterials (magnesium phyllosilicate [1], metal-organic frameworks (MOF) [2], and covalent-organic frameworks (COF) [3]), the fabrication of electrodes with unique properties (e.g., transparency) using carbon nanomaterials [4][5][6][7] or new nanotechnologies [8,9], and applications of electrochemical sensors [10,11].…”

“…PEI and carboxylic SWCNT were deposited on soda lime glass substrates to fabricate the thin film electrode, and its stability was tested in different solvents. By optimizing the number of depositions, transparency in the MIR range and conductivity, the electrode with suitable thickness of film enables a reduction of 20% in the MIR's transparency compared with that of the thickest SWCNT layers, while its sheet resistance can be decreased to 150-200 kW/sq [6].…”