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
Artikel i vetenskaplig tidskrift, 2017

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.

Författare

P. Cai

Guilin University of Electronic Technology

Xiaofeng Xu

Kemi och kemiteknik, Tillämpad kemi, Polymerteknologi

J. M. Sun

South China University of Technology

J. W. Chen

South China University of Technology

Y. Cao

South China University of Technology

RSC Advances

2046-2069 (ISSN)

Vol. 7 20440-20450

Ämneskategorier

Polymerkemi

Materialkemi

Den kondenserade materiens fysik

DOI

10.1039/c7ra01049d