Doping and Thermoelectric Behaviors of Donor-Acceptor Polymers with Extended Planar Backbone

Design of Donor–Acceptor Polymer Semiconductors for Optimizing Combinations with Dopants to Maximize Thermoelectric Performance

“…Subsequently, σ was calculated from the measured sheet resistance and thickness values. S was measured using homemade equipment used in our previous studies. ,,, In detail, the polymer film was placed between two Peltier devices (1 cm apart), each of which was operated using a Keithley 2400 source meter, to induce temperature differences. The thermovoltage was measured using a Keithley 2182A nanovoltmeter, and the temperature was measured using a Keithley 2700 multimeter.…”

“…Developing strategies for improving the power factor ( PF , S 2 σ) of organic materials is a key issue because most organic semiconductors exhibit low κ. − In this regard, significant efforts have been devoted for improving the PF of conjugated polymers. The strategies involved generally focus on (1) the molecular design of the polymer backbone, (2) structural modification to induce self-assembly, and (3) enhancement of the doping efficiency with adequate dopants. − For example, a variety of donor–acceptor (D-A) conjugated polymers have been designed to enhance charge transport by controlling electron-donating/withdrawing properties. − The structures of both the backbone and side chains induce significant molecular ordering, leading to the efficient transport of charge carriers. By optimizing the combination of suitable dopants for D-A conjugated polymers, dominant doping behavior that results in enhanced TE performance can be achieved.…”

Optimizing the doping efficiency and thermoelectric properties of isoindigo-based conjugated polymers using side chain engineering

“…Inherently conjugated polymers exhibit relatively low σ , and chemical doping, which occurs alongside the charge transfer between the host polymer and dopant molecules, is indispensable for increasing the carrier concentration in doped polymer films. The dopants (usually FeCl 3 26–41 and 7,7,8,8-tetracyanoquinodimethane (TCNQ) 42–54 derivatives used for p-doping) tend to aggregate from phase separation, and the charge transport of the pristine polymers is interrupted, resulting in a low σ and thus low PF value. Consequently, the doping efficiency ( η d ) significantly depends on the miscibility between polymer and dopant as well as their corresponding microstructures.…”

A heavily doped D–D′-type polymer with metal-like carrier transport via hybrid doping

“…17–20 Therefore, fine modulation of the carrier generation and transport in doped states is required. 21,22 The carrier generation, transport, and resulting TE properties are strongly dependent on both the molecular design (or structure) and the specific doping method, which have received little attention so far and few systematic studies have been reported. Fundamental studies on how to achieve degenerate doping with metal-like carrier transport are necessary to further optimize organic TE devices.…”