Air-stable n-type thermoelectric materials are recognized as an important and challenging topic in organic thermoelectrics (OTEs) because conventional n-type OTE materials prepared by chemical doping are highly volatile upon exposure to air. Besides, doping efficiency and microstructure are hard to control with the incorporation of external dopants. We report herein the design and synthesis of unconventional n-type OTE materials based on the diradicaloids 2DQQT-S and 2DQQT-Se, which are proved to be neutral single-component organic conductors that exhibit an unprecedented air stability. Without external n-doping, a pristine film of 2DQQT-Se shows an electrical conductivity as high as 0.29 S cm-1 delivering a power factor of 1.4 μW m-1 K-2 . Under ambient conditions, no decay in electrical conductivity is observed for over 260 hours. This work demonstrates that diradicaloids are promising candidates for air-stable and high-performance OTE materials.
Keywords: conducting materials; diradicaloids; n-type thermoelectric materials; organic thermoelectrics; self-doping.
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