1452871-20-3Relevant articles and documents
The role of conjugated side chains in high performance photovoltaic polymers
Wang, Meng,Ma, Di,Shi, Keli,Shi, Shaowei,Chen, Song,Huang, Changjiang,Qiao, Zi,Zhang, Zhi-Guo,Li, Yongfang,Li, Xiaoyu,Wang, Haiqiao
, p. 2802 - 2814 (2015)
Four new D-A type copolymers, namely, PBDT-DFQX-PP, PBDT-DFQX-TP, PBDT-DFQX-PT and PBDT-DFQX-TT, were designed and synthesized to investigate the influence of conjugated side chain pattern on photovoltaic properties of conjugated polymers. All the four copolymers have an identical conjugated backbone comprising benzo[1,2-b:4,5-b′]dithiophene (BDT) donor unit and quinoxaline (Qx) acceptor unit, but with varying conjugated side chains, p-alkoxyphenyl or 2-alkylthienyl, attached to the donor and acceptor units, respectively. As evidenced by UV/Vis absorption spectra, electrochemical cyclic voltammetry, density functional theory (DFT), grazing incidence X-ray scattering (GIXS), transmission electron microscope (TEM) and photovoltaic measurements, the difference in conjugated side chain modulation led to totally different physicochemical properties. Among the four copolymers, PBDT-DFQX-TT exhibits the broadest absorption spectrum, the most close-packed structure as well as a finest fibril structure when blended with PC71BM. After systematic device optimization, the power conversion efficiencies (PCEs) of the bulk heterojunction (BHJ) photovoltaic devices based on the blends of PBDT-DFQX-PP, PBDT-DFQX-TP, PBDT-DFQX-PT and PBDT-DFQX-TT with PC71BM achieved 3.96%, 6.08%, 6.54% and 7.68%, respectively. By systematic varying the side chains of the copolymers from all phenyl groups to all thienyl ones, PCEs was increased by 250% from 3.96% to 7.68%. To date, PBDT-DFQX-TT is one of a few Qx-based PSCs that exhibits PCE exceeding 7.5%, and the results suggest that simultaneously modulating the conjugated side chains on both donor and acceptor units of copolymers could be an effective strategy for constructing high performance photovoltaic copolymers.
New alkoxylphenyl substituted benzo[1,2-b:4,5-b′] dithiophene-based polymers: Synthesis and application in solar cells
Yuan, Jun,Xiao, Lu,Liu, Bo,Li, Yongfang,He, Yuehui,Pan, Chunyue,Zou, Yingping
, p. 10639 - 10645 (2013/09/23)
Two new alkoxylphenyl substituted benzo[1,2-b:4,5-b′]dithiophene (BDTPO)-based polymers (PBDTPO-DTBO and PBDTPO-DTBT) were synthesized. Their structures were verified by NMR spectroscopy, the molecular weights were determined by gel permeation chromatography (GPC), and the thermal properties were investigated by thermogravimetric analysis (TGA). UV-Vis absorption spectra of the polymers show broad and strong absorption bands from 300-750 nm both in CHCl3 solutions and films. The resulting copolymers exhibit relatively deep HOMO energy levels (-5.56 and -5.46 eV) and surprisingly high hole mobilities (2.2 × 10-1 and 3.3 × 10-2 cm2 V-1 s-1) for PBDTPO-DTBO and PBDTPO-DTBT, respectively. Preliminary photovoltaic properties of the copolymers blended with [6,6]-phenyl-C71 (or 61)-butyric acid methyl ester (PCBM) as an electron acceptor were investigated. The polymer solar cell (PSC) based on the single layer device structure of ITO/PEDOT:PSS/PBDTPO-DTBO:PC71BM (1:1.5, w/w)/Ca/Al demonstrates a high power conversion efficiency of 6.2% under the illumination of AM 1.5G, 100 mW cm-2.
