posted on 2021-07-06, 15:33authored byYang Min, Changshuai Dong, Hongkun Tian, Jun Liu, Lixiang Wang
Organic thermoelectric materials
play a vital role in flexible
power generating applications, such as wearable electronics and sensor
networks. While there is a wealth of research on p-type organic thermoelectric
materials, developments on n-type counterparts as complementary are
comparatively limited. Herein, we report a new kind of n-type small-molecule
thermoelectric materials based on B←N-incorporated dibenzo-azaacenes 1,2-DBNA-2 and 1,2-DBNA-5. Because of the low-lying
lowest unoccupied molecular orbital (LUMO) energy levels, 1,2-DBNA-2 and 1,2-DBNA-5 could be efficiently n-doped, and the
rigid and almost planar skeleton could ensure good carrier transfer.
When doped with a typical n-dopant (4-(1,3-dimethyl-2,3-dihydro-1H-benzoimidazol-2-yl)phenyl)dimethylamine (N-DMBI), 1,2-DBNA-5 exhibits a moderate conductivity
of 0.01 S cm–1 and a power factor of 0.06 μW
m–1 K–2 with a Seebeck coefficient
of −244.4 μV K–1 in thermoelectric
devices. These results not only demonstrate that B←N-incorporated
dibenzo-azaacenes are a novel class of n-type thermoelectric materials
but also highlight a new strategy to develop n-type organic thermoelectric
materials.