ABSTRACT Organic n‐type polymers usually suffer from relatively low electrical conductivity which hampers their application as an active layer for thermoelectrics. Molecular dopants such as benzimidazol‐2‐yl‐N, N‐dimethylbenzenamine (N‐DMBI) are often employed to improve the polymer's electrical conductivity. It was found that 2,2,6,6‐tetramethyl‐1‐piperidinyloxy (TEMPO) radical can be employed to improve N‐DMBI doping efficiency of a bicomponent blend via hydrogen transfer. Herein, we report on a novel n‐type conjugated polymer with TEMPO radical moieties attached to the side chains, whose conjugated core is formed by two electron‐deficient units, i.e. diketopyrrolopyrrole (DPP) and isoindigo (IID). We show that the electrical conductivity of such TEMPO‐functionalized polymer increases up to 4 orders of magnitude upon blending with N‐DMBI resulting in a power factor of 0.6 µW m −1 K −2 . Additionally, a reference polymer without side‐chain TEMPO functionalization was synthesized that did not feature a significant conductivity increase. Our work shows that attaching TEMPO radical units to the side chains of an n‐type conjugated polymer is a suitable strategy to boost the doping efficiency of N‐DMBI. Our findings contribute to the design of novel n‐type conjugated polymers that feature high thermoelectric performances upon blending with a molecular dopant.
Jiang et al. (2026) studied this question.