Self-Consistent Charge Density Functional Tight-Binding Study of Poly(3,4-ethylenedioxythiophene): Poly(styrenesulfonate) Ammonia Gas Sensor

Abstract

Geometric and electronic properties of 3,4-ethylenedioxythiophene (EDOT), styrene sulfonate (SS), and EDOT: SS oligomers up to 10 repeating units were studied by the self-consistent charge density functional tight-binding (SCC-DFTB) method. An application of PEDOT:PSS for ammonia (NH3) detection was highlighted and investigated both experimentally and theoretically. The results showed an important role of H-bonds in EDOT:SS oligomers complex conformation. Electrical conductivity of EDOT increased with increasing oligomers and doping SS due to enhancement of π conjugation. Printed PEDOT:PSS gas sensor exhibited relatively high response and selectivity to NH3. The SCC-DFTB calculation suggested domination of direct charge transfer process in changing of PEDOT:PSS conductivity upon NH3 exposure at room temperature. The NH3 molecules preferred to bind with PEDOT:PSS via physisorption. The most favorable adsorption site for PEDOT:PSS-NH3 interaction was found to be at the nitrogen atom of NH3 and hydrogen atoms of SS with an average optimal binding distance of 2.00 Å.Electronic supplementary materialThe online version of this article (doi:10.1186/s11671-017-1878-2) contains supplementary material, which is available to authorized users.

Adsorption of NO2, HCN, HCHO and CO on pristine and amine functionalized boron nitride nanotubes by self-consistent charge density functional tight-binding method

“…The SCC-DFTB provided the molecular structures, energies and electronic properties in excellent agreement with DFT methods but was ∼100-1000 times faster. The SCC-DFTB can also include reliable description of dispersions and weak interactions (Van der Waals and H-bonding) that are important roles for investigation of gas adsorption on a sensing material which is consistent with experimental observations [40,45,47,48]. Moreover, the SCC-DFTB was proved to be effective in the simulation studies of boron nitride nanostructures systems [49][50][51].…”

“…The SCC-DFTB method is based on a second-order expansion of the DFT total energy expression in term of charge density variation with respect to a reference density [41][42][43][44][45]. The total energy of SCC-DFTB based on the Kohn-Sham orbitals is given by following equation [44]:…”

Neuromorphic Organic Devices that Specifically Discriminate Dopamine from Its Metabolites by Nonspecific Interactions

“…Molecular orbitals and energy values for PEDOT (charge +1) and PSS (charge −1) models are in good agreement with previous works for describing the polaron state. [33,34] The Mulliken charges distribution of the system showed that most of the negative charge (−0.64) in PSS is localized on the sulfonate anion. Then, starting from PEDOT and PSS models, we converged to an optimized PEDOT:PSS model.…”

Flexible alternating current electroluminescent ammonia gas sensor

“…This interaction is specically strong because the NH 3 molecules can directly bind to H atoms of PEDOT:PSS via the lone-pair electrons of the N atoms with a binding distance of 2.00Å and the interaction energy of 6.596 kcal mol À1 according to a theoretical study using the selfconsistent charge density functional tight-binding method. 27 As a result of the charge transfer from the adsorbed NH 3 molecules to PEDOT:PSS, the number of holes decreases and the depletion region thickness of the PEDOT:PSS layer increases, leading to the expansion of the neutral polymer backbone region and the increase in the resistance. Thus, the EL intensity of sensor reduces in the presence of NH 3 and recovers to its initial value in the absence of NH 3 molecules.…”