Band Gap Tuning in Composites of Polypyrrole Derivatives and C₆₀Pd₃ Polymer as Models for p–n Junction: A First Principle Computational Study

Abstract

In this work, the electronic properties of a substituted polypyrrole (PPy−R) deposited on a palladium–fullerene polymer (C60Pd2(‐2Pd)) were obtained by first principles DFT+vdW calculations. By introducing both electron‐withdrawing (COOH) and electron‐donating (NH2) substituents into the polypyrrole chain, we modulated the HOMO and LUMO levels of PPy−R/C60Pd2(‐2Pd). Furthermore, we also determined the influence of the second COOH group in each pyrrole ring and the CH3 group linked to the nitrogen atom on the electronic properties. The calculated data show that the type of substituent, as well as the termination of the palladium–fullerene polymer, strongly influences the band gap. The general picture of the mixed systems reveals that the HOMO corresponds to that of PPy/PPy−R and the LUMO corresponds to that of C60Pd2(‐2Pd). For isolated PPy−R, the substituent strongly influences the relative position of the HOMO and LUMO levels toward the vacuum level, and, based on this fact, we can easily tune the band gap of the mixed systems. For the sake of completeness, all configurations, as well as the corresponding total binding energies, were carefully analysed and compared. The adsorption of PPy(‐R) on the Pd‐terminated C60Pd2 led to the formation of surface Py⋅⋅⋅Pd complexes that have higher binding energies than in the case of the C60‐terminated polymer. Furthermore, composites with two PPy chains on C60Pd2 (‐2Pd) were also studied.

Polypyrrole Nanoparticles Doped with Fullerene Uniformly Distributed in the Polymeric Phase: Synthesis, Morphology, and Electrochemical Properties

“…The degree of this shift depends on the number of pyrrole units in the oligomeric structure. This effect is in perfect agreement with our previous results where we analyzed the electronic properties of polypyrrole and pyrrole oligomers calculated at the DFT­(PBE)+D2 level of theory (see Table 1 in ref ). The longer n -pyrrole oligomers have higher HOMO levels relative to those for the shorter ones (−5.10 eV for 1-pyrrole and −3.46 eV for 10-pyrrole).…”

Oxidized MWCNTs as an Oxidizing Agent and Dopant in MWCNT@Polypyrrole Composite Formation**

“…The most important issue in the modeling of PPY/ox-SWCNT(10,0) was the mutual matching of the two components to maintain periodicity. By taking three unit cells of the optimized pyrrole dimer (3 d PPY is 21.52 Å [94] ), we obtained a very good lattice match.…”

“…Figure 14 shows the total and projected DOS for the PPy/ox-SWCNT(10,0) system calculated at the DFT(PBE) + D3(BJ) level of theory. The polymer exhibited metallic properties, where the unoccupied bands just above the Fermi level corresponded to those of the HOMO state of the isolated PPY [94] combined with the carbon states of the nanotube. Figure 14 also shows the plot of the charge density for these empty states (0-0.1 eV).…”

Fullerene‐Based Conducting Polymers:n‐Dopable Materials for Charge Storage Application

“…Organic polymers exhibit electrochemical activity in a positive potential range. Because of the partial electron transfer between fullerenes and π-conjugated polymers, [108][109][110] the oxidation potential of the polymeric component of the composite is shifted toward a more positive potential than the oxidation potentials of pristine polymers formed under the same conditions. The voltammetric behavior of fullerene component depends on its structure.…”