Theoretical and Experimental Characterization of Small Band Gap Poly(3,4-ethylenedioxythiophene methine)s

Abstract

Theoretical and experimental characterization of relatively small band gap methine-bridged poly(3,4-ethylenedioxythiophene)(PEDOT) derivatives is reported. AM1 and the modified extended Hückel theory were used to explore the ground-state geometric and electronic structures of poly[(3,4-ethylenedioxythiophene-2,5-diyl) methine] (PEDOT-M). The bond length alteration in PEDOT-M was found to be smaller than that in the reported methine-bridged polythiophene, and this resulted in a significantly lower band gap of 0.48 eV in PEDOT-M. The structure and properties of the methine-bridged PEDOT were further verified by synthesis of poly[(3,4-ethylenedioxythiophene-2,5-diyl)-benzylidene] (PEDOT-B) and poly[(3,4-ethylenedioxythiophene-2,5-diyl)-(p-methoxybenzylidene)] (PEDOT-MB). These polymers were found to be highly dehydrogenated and to contain a conjugated backbone of alternating aromatic and quinoid ethylenedioxythiophene segments. The optical and electrochemical band gaps of PEDOT-B are 0.87 and 1.05 eV, respectively, while those of PEDOT-MB are 0.86 and 1.01 eV. The methoxy substitution of PEDOT-MB results in a smaller ionization potential and electron affinity than those of PEDOT-B. The theoretical and experimental results show that methine-bridged PEDOT is a small band gap polymer.

Synthesis and photovoltaic properties of alternative copolymers of benzo[1,2-b:4,5-b′]dithiophene and thiophene

“…The bandgap as well as the molecular energy level of P(BDT-T) is similar with that of H6, the results indicated that different alkoxyl chains on the BDT unit influence the energy bandgap of polymers very little. The electrochemical bandgap of P(BDT-T) and P(BDT-TT) is a little higher than that of the optical bandgap aforementioned, which is a common phenomenon for the conjugated polymers [42,43].…”

Temperature dependence of band gaps and conformational disorder in PEDOT and its selenium and tellurium derivatives: Density functional calculations

“…For PEDOT and derivatives thereof, absorption spectroscopy indicates that the difference in the gap is less than 0.1 eV between PE-DOT in solution and PEDOT in film form. 38,40 The computed band gap also depends quite sensitively on the computational approach used. Especially the discontinuity in the exchange-correlation functional is often pointed out as the main source of error.…”

Study on the Interaction between BSA and a Water-Soluble Cationic Poly(heteroarylene methine) Bearing Pyridinium Salts

“…Poly(heteroarylene methine)s, are a kind of conjugated polymers, which are promising materials since they are low band gap polymers which have attractive a great deal of attention due to their intrinsic electronic, optoelectronic, optical and nonlinear properties [15]. Little study has been reported about water-soluble poly(heteroarylene methine)s, although water-soluble conjugated polymers have been extensively investigated for chemical and biological sensing applications.…”