A. K. Bakhshi

Electronic structure and conduction properties of copolymers of silole based donor–acceptor polymers: effect of multi-neighbour interaction

Abstract Using the ab initio band structure results of two novel silole based donor–acceptor polymers PSICF (A)x and PSICN (B)x, the electronic structures and conduction properties of their various quasi-one-dimensional superlattices (copolymers) (AmBn)x, belonging to the class of type-II staggered superlattices, have been investigated using negative factor counting method taking into account multi-neighbour interaction. Both PSICF and PSICN consist of a bicyclopentadisilole unit bridged by an electron-accepting group Y (Y=CCF2 in PSICF and Y=CC(CN)2 in PSICN). The trends in the electronic structures and conduction properties of these copolymers (AmBn)x as a function of the (i) block sizes m and n; (ii) composition (m/n) and (iii) arrangement of blocks (periodic or aperiodic) in the copolymer chain are discussed. The results obtained are important guidelines for designing copolymers with tailor-made conduction properties.

Computational atomistic blueprinting of novel conducting copolymers using particle swarm optimization

A proficient metaheuristic approach viz., particle swarm optimization coupled with negative factor counting technique and inverse iteration method has been employed for designing novel binary and ternary copolymers based on thiophene, pyrrole and furan skeletons. A comparative study of the electronic structures and conduction properties of neutral heterocyclic copolymers and their benzene substituted analogues is inferred using the band structure results derived from ab-initio Hartree–Fock crystal orbital calculations. The band gap value decreases as a result of substitution on the polymer backbone due to increased quinoid contributions which is expected to enhance the intrinsic conductivity of the resulting copolymers. In general, it has been found that HOMO energies have a more decisive influence than LUMO energies on the relative fraction of constituents of the respective low band gap copolymers. The trends in the electronic properties of the respective copolymers are also verified and discussed with the help of density of states. These results can help streamline scrupulous synthetic efforts providing a potent route for molecular engineering of sustainable and efficient electronic materials.

Sol-Gel derived CeO2:TiO2 coatings for electrochromic devices

Thin films of mixed CeO2-TiO2 with different Ce/Ti mole ratios were prepared following an alcohol based sol-gel route via the spin coating technique using mixed inorganic-organic [CeCl3.7H2O and Ti(OPr)4] precursors. Ion storage capacity for films obtained from aged sols was observed to be high. Enhanced titanium oxide content improved the insertion capacity of the corresponding films as was evident from inserted charge determined by multiple step chronoamperometric measurements. Electrochemical, optical, structural and thermal performances showed the suitability of the films in an all solid state electrochromic (transmissive) device with tungsten trioxide (WO3) as electrochromic material and a conductive polymeric electrolyte based on lithium.

Molecular Engineering of Electrically Conducting Polymers Using Artificial Intelligence Methods

The scientific propensity in the field of organic conducting polymers has witnessed growing professional interest and commercial investment over the last three decades, catalyzing new developments in electronics as well as bioanalytical industries. A great deal of efforts has been made both experimentally and theoretically to develop application-specific conducting polymers. But the challenging task that still remains is the achievement of a minimum value of band gap which governs the electrical, optical and magnetic properties of the polymer. In view of the complexity of the problem, some interesting nature-inspired metaheuristic optimization algorithms have recently been employed for tailoring conducting polymers with optimal electrical properties. In the present review, the scope of some optimization algorithms for theoretical modeling of conducting polymers has been discussed. Some recent interesting results on theoretical investigations on various conducting polymers are presented.