Syntheses and Properties of Conjugated Polymers Containing Thieno[2,3‐b]indole with Different Electron‐deficient Units

Abstract

New conjugated polymers using electron‐rich unit, thieno[2,3‐b]indole (2‐TI), and various electron‐deficient units were synthesized for the utilization in the photovoltaics. The synthesized polymers (PTIBTI, PTITPD, and PTIID) with various types of electron‐deficient units showed different electronic structure and properties. The PTITPD provides the higher VOC through suitable energy level offset of LUMO (donor)‐LUMO (PC71BM) and improved JSC resulting from better crystallinity, charge carrier mobility and morphology, leading to the higher PCE value of OPV out of the series. This result illustrates that the combination of various electron‐deficient units affects the electronic structure, such as the HOMO/LUMO energy levels and bandgap in addition to the morphology and the carrier mobility, implying that variation of the electron‐deficient unit should be explored for the utilization of a given electron‐rich unit to produce the better performance of the device.

Rational design of the S,N‐heteroacene‐based nonfullerene by introducing the fluorine atom for efficient high‐performance organic solar cells

“…These results demonstrate that the well‐mixed and homogeneous film morphology of PBDB‐T‐2F:DTP‐2F device has played an important role in improving performances. The well‐mixed and homogeneous morphology of PBDB‐T‐2F:DTP‐2F blend film indicates the best blend film morphology performance, which affect to the charge extraction and transport as well as higher FF 26 …”