A series of fully fused n-type mixed conduction lactam polymers p(g₇NC_nN), systematically increasing the alkyl side chain content, are synthesized via an inexpensive, nontoxic, precious-metal-free aldol polycondensation. Employing these polymers as channel materials in organic electrochemical transistors (OECTs) affords state-of-the-art n-type performance with p(g₇NC₁₀N) recording an OECT electron mobility of 1.20 × 10^–2 cm² V^–1 s^–1 and a μC* figure of merit of 1.83 F cm^–1 V^–1 s^–1. In parallel to high OECT performance, upon solution doping with (4-(1,3-dimethyl-2,3-dihydro-1H-benzoimidazol-2-yl)phenyl)dimethylamine (N-DMBI), the highest thermoelectric performance is observed for p(g₇NC₄N), with a maximum electrical conductivity of 7.67 S cm^–1 and a power factor of 10.4 μW m^–1 K^–2. These results are among the highest reported for n-type polymers. Importantly, while this series of fused polylactam organic mixed ionic–electronic conductors (OMIECs) highlights that synthetic molecular design strategies to bolster OECT performance can be translated to also achieve high organic thermoelectric (OTE) performance, a nuanced synthetic approach must be used to optimize performance. Herein, we outline the performance metrics and provide new insights into the molecular design guidelines for the next generation of high-performance n-type materials for mixed conduction applications, presenting for the first time the results of a single polymer series within both OECT and OTE applications.

Photothermal therapy (PTT) is a highly effective therapeutic modality in tumor therapy. Nevertheless, the PTT of cancer is also accompanied by thermoresistance of cells, which may alleviate the PTT efficacy or even lead to tumor recurrence. Heat shock protein 90 (HSP90) is closely related to the resistance, so a combination of inhibitors of HSP90 and photothermal agents could improve the PTT efficacy. In this work, gambogic acid (GA), an inhibitor of HSP90, is incorporated into a photothermal nanoagent, so as to reduce the influence of thermoresistance and maximize the PTT efficiency. Poly((2,5-diyl-2,3,5,6-tetrahydro-3,6-dioxo-pyrrolo(3,4-c)pyrrole-1,4-diyl)-alt-(2,2′:5′,2′′-terthiophene-5,5′′-diyl)) (PDPP3T) is selected as the robust photothermal material, and polymer-GA nanoparticles (PGNPs) incorporating both GA and PDPP3T are prepared. The PGNPs exhibit excellent photothermal activity with a high photothermal conversion efficiency of 36%, and great heating reproducibility and photoacoustic imaging performance. Besides, PGNPs are stable enough in water, in physiological conditions or under irradiation. The inhibition of HSP90 dramatically increases the apoptosis rate of cells, accordingly promoting the efficacy of PTT. Mice treated with PGNPs under 808 nm laser irradiation possess the most effective tumor inhibition, while no obvious systemic toxicity has been observed. Our study provides a valid approach to improve the PTT efficacy for more potent cancer therapy.