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Effects of including electron-withdrawing atoms on the physical and photovoltaic properties of indacenodithieno 3,2-b thiophene-based donor-acceptor polymers: towards an acceptor design for efficient polymer solar cells

P. Cai ; Xiaofeng Xu (Institutionen för kemi och kemiteknik, Polymerteknologi) ; J. M. Sun ; J. W. Chen ; Y. Cao
RSC Advances (2046-2069). Vol. 7 (2017), 33, p. 20440-20450.
[Artikel, refereegranskad vetenskaplig]

Three new D-A polymers PIDTT-DTBO, PIDTT-DTBT and PIDTT-DTFBT, using indacenodithieno[3,2-b] thiophene (IDTT) as the electron-rich unit and benzoxadiazole (BO), benzodiathiazole (BT) or difluorobenzothiadiazole (FBT) as the electron-deficient unit, were synthesized via a Pd-catalyzed Stille polymerization. The included electron-withdrawing atoms of the acceptor portion were varied between O, S, and F for tailoring the optical and electrochemical properties and the geometry of structures. Their effects on the film topography, photovoltaic and hole-transporting properties of the polymers were thoroughly investigated via a range of techniques. As expected, the stronger electron-withdrawing BO unit affords red-shifted absorption, low-lying HOMO and LUMO levels for the polymer PIDTT-DTBO. However, it depicts lower hole mobility and a less efficient charge collection in the active layer compared to the polymer PIDTT-DTBT. In addition, degradation of the solubility is observed in the fluorinated polymer PIDTT-DTFBT. As a result, a BHJ PSC (ITO/PEDOT: PSS/polymer: PC71BM/interlayer/ Al) fabricated with PIDTT-DTBT attains the best power conversion efficiency (PCE) of 4.91%. These results thus demonstrate the potential effects of electronegative atoms on IDTT-based polymers and the structure-function correlations of such electron-donor materials for efficient PSCs.

Denna post skapades 2017-05-17. Senast ändrad 2017-09-07.
CPL Pubid: 249406


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