Strategies and concepts in n-doped conjugated polymer thermoelectrics

From a power factor of merely 10−1 μW m−1 K−2 using traditional naphthalene diimide n-type polymers and the tetrakis(dimethylamino)ethylene electron-donor dopant to 80 μW m−1 K−2 using the new benzodifurandione-based oligo(p-phenylene vinylene) n-type polymers and triaminomethane hydride-donor dopant, we have witnessed ground-breaking record developments in n-doped conjugated polymer thermoelectrics in the past few years. In this review, we discuss various strategies and concepts in chemical structure engineering for both n-type conjugated polymers and n-dopants that have brought about this huge improvement in the performance of n-doped conjugated polymer thermoelectrics, using examples from the current literature. Device considerations such as air and thermal stabilities, as well as contact resistance, are also elaborated.