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Recently, organic thermoelectric (TE) materials have been intensively studied because of their great potential for application in flexible/wearable TE generators for power generation at low temperatures. However, reports on the...

Two types of p-type thermoelectric (TE) polymers with alkyl (PCPDTSBT) and oligoethylene glycol (OEG) side chains (PCPDTSBT-A) on an sp 2 -hybridized olefinic bis-(alkylsulfanyl)methylene-substituted cyclopentadithiophene backbone are synthesized. Interestingly, the OEG-substituted polymer, PCPDTSBT-A, exhibits significant self-doping compared to PCPDTSBT, where the polaron density of the former is 2.3 × 10 16 mm −3 (vs 7.9 × 10 14 mm −3 for PCPDTSBT) without external doping. Changing the side chains also induces a completely different polymer chain orientation in the PCPDTSBT-A (face-on) and PCPDTSBT (edge-on) films. The effect of doping with 2,3,5,6-tetrafluoro-7,7,8,8-tetracyanoquinodimethane (F 4 TCNQ) on the morphological and TE properties of the polymers with different side chains is studied. Sequential solution doping (SQD) is performed by overcoating the preannealed polymer films with F 4 TCNQ solution, which affords highly effective doping without disrupting the morphology of the crystalline films, especially for PCPDTSBT-A with OEG side chains. Resulting from the synergistic effect of the OEG side chains and SQD, PCPDTSBT-A exhibits remarkably improved electrical conductivity (53.8 S cm −1 ) with a higher power factor (40.4 μW m −1 K −2 ), compared to PCPDTSBT, for which the maximum electrical conductivity is 1.4 S cm −1 and the power factor is 1.8 μW m −1 K −2 . In addition, the transport coefficient of PCPDTSBT-A, determined by applying the Kang−Snyder model (2.40 × 10 −2 S cm −1 ), is superior to that of PCPDTSBT (3.59 × 10 −3 S cm −1 ), thereby showing the excellence of the developed strategy for improving the performance of TE polymers.

A dual-band on-body antenna for a wireless body area network repeater system is proposed. The designed dual-band antenna has the maximum radiation directed toward the inside of the human body in the medical implantable communication service (MICS) band in order to collect vital information from the human body and directed toward the outside in the industrial, scientific, and medical (ISM) band to transmit that information to a monitoring system. In addition, the return loss property of the antenna is insensitive to human body effects by utilizing the epsilon negative zeroth-order resonance property.

Three p‐type thermoelectric (TE) polymers based on the indacenodithiophene moiety substituted with bis(alkylsulfanyl)methylene side‐chains (IDTS) are synthesized. The TE characteristics of IDTS‐based donor–donor’ (D–D′) type PIDTSDTTT and donor–acceptor (D–A) type polymers, PIDTSBT and PIDTS2FBT are investigated. Remarkably higher electrical conductivity (σ = ≈1000 S cm−1) and power factor (PF = ≈120 μW m−1 K−2) by doping with AuCl3 are measured for PIDTSDTTT compared to D–A type polymers. The higher σ of PIDTSDTTT originates from its higher carrier concentration compared to those of PIDTSBT and PIDTS2FBT. Moreover, the facile polaron‐to‐bipolaron transition is measured, and the charge carriers are calculated to be more stable with extended delocalization in PIDTSDTTT compared to D–A polymers. The significantly higher doping stability in PIDTSDTTT can be explained in terms of the higher conduction band of bipolarons than the valence band of O2 and H2O, which blocks the facile reduction of bipolarons in air. The energetic structures of doped polaron and bipolaron states, as well as pristine TE polymers, must be carefully considered to realize efficient and stable p‐type thermoelectric polymers, where a D–D′ type structure with further enhanced carrier mobility can be considered as a potential molecular framework.