Dichlorinated Dithienylethene-Based Copolymers for Air-Stable n-Type Conductivity and Thermoelectricity

摘要

Two donor-acceptor (D-A) polymers are obtained by coupling difluoro- and dichloro-substituted forms of the electron-deficient unit BDOPV and the relatively weak donor moiety dichlorodithienylethene (ClTVT). The conductivity and power factors of doped devices are different for the chlorinated and fluorinated BDOPV polymers. A high electron conductivity of 38.3 and 16.1 S cm(-1) are obtained from the chlorinated and fluorinated polymers with N-DMBI, respectively, and 12.4 and 2.4 S cm(-1) are obtained from the chlorinated and fluorinated polymers with CoCp2, respectively, from drop-cast devices. The corresponding power factors are 22.7, 7.6, 39.5, and 8.0 mu W m(-1) K-2, respectively. Doping of PClClTVT with N-DMBI results in excellent air stability; the electron conductivity of devices with 50 mol% N-DMBI as dopant remained up to 4.9 S m(-1) after 222 days in the air, the longest for an n-doped polymer stored in air, with a thermoelectric power factor of 9.3 mu W m(-1) K-2. However, the conductivity of PFClTVT-based devices can hardly be measured after 103 days. These observations are consistent with morphologies determined by grazing incidence wide angle X-ray scattering and atomic force microscopy.