Band gap engineering for poly(p‐phenylene) and poly(p‐phenylene vinylene) copolymers using the tight‐binding approach

Abstract

ABSTRACT:The interest in poly(p-phenylene) (PPP) and poly(p-phenylene vinylene) (PPV) copolymers stems from the fact that these homopolymers present interesting optical and electronic properties that allow a great variety of technological applications. Combining different numbers of PPP and PPV units it is possible, in principle, to obtain new structures presenting intermediate gap values (2.8 eV and 2.4 eV for PPP and PPV, respectively). For this study we used a Hü ckel Hamiltonian tight-binding coupled to the negative factor counting (NFC) technique. We carried out a systematic search to determine optimum relative concentrations for disordered binary polymeric alloys with predefined gap values. Once these structures were obtained, we used the semiempirical methods AM1/PM3 and ZINDO/S-CI for geometrical and optical studies, respectively. Our theoretical results show that it is possible to obtain copolymers of PPP and PPV with intermediate gap values of their parent structures.

Quasi one-dimensional band dispersion and surface metallization in long-range ordered polymeric wires

“…The gap for freestanding PPP is expected to be 2.9 eV on the basis of the TB approach 55 . Assuming the PPP polymer as being a 3 p -type AGNR with p =1 and w =2.4 Å ( Supplementary Fig.…”

Spectroscopic ellipsometry as a complementary tool for studying luminescent polymers: Poly(p-phenylenevinylene) as a particular case

“…Different approaches have been used for determining the energy gap of PPV, which was assumed to be 2.8 eV [20], a value higher than that obtained from theoretical modeling [21], and also, electrochemical and optical measurements [19], i.e. 2.4 eV.…”

Theoretical analysis of aggregation in block‐copolymer films: The optical signature

“…In our case, results obtained with AM1 and PM3 for the geometry of LaPPS19 monomers are in reasonable agreement. As AM1 presents better results for dihedral angles for some organic molecules 40, 41, an important parameter with a significant influence on optical properties, we have chosen AM1 to carry out the geometrical optimizations for the smaller systems, isolated monomer, dimer, and trimer (see Fig. 3).…”