Synthesis and photovoltaic behaviors of narrow‐band‐gap π‐conjugated polymers composed of dialkoxybenzodithiophene‐ and thiophene‐based fused aromatic rings

Abstract

Abstractπ‐Conjugated polymers, PBDT‐CNETT and PBDT‐CNECPDT, were prepared by the Stille cross‐coupling polymerization. Optical and thermal properties of the obtained polymers were investigated by UV–vis spectroscopy and thermogravimetric analysis. PBDT‐CNETT and PBDT‐CNECPDT exhibited very narrow band gaps of 1.39 and 1.13 eV, respectively. Highest occupied molecular orbital energy levels estimated by surface analyzer were −5.17 and −5.11 eV for PBDT‐CNETT and PBDT‐CNECPDT, respectively. The solar cells based on these polymers were evaluated with the cell configuration of ITO/PEDOT‐PSS/polymer:PC61BH/LiF/Al. The power conversion efficiencies of the solar cells were estimated to be 1.57 and 0.16% for PBDT‐CNETT and PBDT‐CNECPDT, respectively. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011

Synthesis of novel conjugated polymers comprising modified cyclopentadithiophene units in the main chain

“…The estimated optical band gaps of P1 and P2 are in a good agreement with the literature data for a CPDT-fluorene copolymer bearing dicyanovinyl groups at the bridge positions (E g ¼ 1.13 eV). 19 Polymer P3 also demonstrates three distinct bands in the absorption spectrum. The broad low-energy band has an offset at approximately 700 nm corresponding to the E g * 1.76 eV.…”

“…It should be noted that application of a similar cyanovinyl monomer for designing benzodithiophenebased conjugated polymers was reported previously by other research group. 19…”

Ethynylene‐Linked Oligomers Based on Benzodithiophene: Synthesis and Photoelectric Properties

“…The results showed that their optical band gaps were 1.92 and 2.27 eV, respectively. For the construction of small band gap polymers, many examples [40,41] have demonstrated that utilizing alternative electron deficient and electron rich units is an effective method. The difference of optical band gap is particularly owed to the different molecular structures and the number of electron donating functional groups.…”

Benzo[1,2-b:4,5-b′]dithiophene-based conjugated polymers: band gap and energy level control and their application in polymer solar cells

“…The derivatives, P7, P8 and P9 were designed and a 1.13 eV band gap was reported in the polymer P8 (Scheme 4). 23,24 Besides introducing electron-rich or electron-deficient side groups, designing conjugated polymer with quinoid structures is another effective way to reduce band gap, and this strategy has been already proved to be very effective in other conjugated systems. For BDT-based polymers, P10 was designed based on this strategy.…”