Acceptor–acceptor (A‐A) copolymerization is an effective strategy to develop high‐performance n‐type conjugated polymers. However, the development of A‐A type conjugated polymers is challenging due to the synthetic difficulty. Herein, a distannylated monomer of strong electron‐deficient double B←N bridged bipyridine (BNBP) unit is readily synthesized and used to develop A‐A type conjugated polymers by Stille polycondensation. The resulting polymers show ultralow LUMO energy levels of −4.4 eV, which is among the lowest value reported for organoboron polymers. After n‐doping, the resulting polymers exhibit electric conductivity of 7.8 S cm−1 and power factor of 24.8 μW m−1 K−2. This performance is among the best for n‐type polymer thermoelectric materials. These results demonstrate the great potential of A‐A type organoboron polymers for high‐performance n‐type thermoelectrics.

Only very few conjugated polymers can be n-doped for thermoelectric applications. In this work, for the first time, we report that incorporation of Boron−Nitrogen coordination bond (B ← N unit) to a donor−acceptor (D−A) type conjugated polymer enable ndoping for thermoelectric application. The incorporation of B ← N unit into the polymer backbone leads to not only a downshift of LUMO/HOMO energy levels by 0.27 eV/0.33 eV, but also diminished intramolecular D−A character of the polymer backbone. As a result, while the control polymer cannot be n-doped, the polymer containing B ← N unit (PI-BN) can be n-doped by 4-(1,3-dimethyl-2,3-dihydro-1H-benzoimidazol-2-yl)-N,N-dimethylaniline (N-DMBI). Finally, PI-BN exhibits an electrical conductivity (σ) of 0.97 × 10 −3 S cm −1 , Seebeck coefficient (S) of −453.8 μV K −1 , and power factor (PF) of 0.02 μW m −1 K −2 when doped with 5 wt % N-DMBI. A great advantage of PI-BN is its excellent miscibility with the ndopant because of its amorphous nature and large pendent substituents. This work indicates that organoboron polymers can be ndoped and can be used for thermoelectrics.

A new n-type p-π* conjugated organic molecule based on triarylborane shows unique alcohol-solubility even in the absence of polar side chains. With its low-lying LUMO/HOMO energy levels and high electron mobility, the molecule can be used as electron acceptor in eco-friendly alcohol-processed organic solar cells.

Typical n‐type conjugated polymers are based on fused‐ring electron‐accepting building blocks. Herein, we report a non‐fused‐ring strategy to design n‐type conjugated polymers, i.e. introducing electron‐withdrawing imide or cyano groups to each thiophene unit of a non‐fused‐ring polythiophene backbone. The resulting polymer, n‐PT1, shows low LUMO/HOMO energy levels of −3.91 eV/−6.22 eV, high electron mobility of 0.39 cm2 V−1 s−1 and high crystallinity in thin film. After n‐doping, n‐PT1 exhibits excellent thermoelectric performance with an electrical conductivity of 61.2 S cm−1 and a power factor (PF) of 141.7 μW m−1 K−2. This PF is the highest value reported so far for n‐type conjugated polymers and this is the first time for polythiophene derivatives to be used in n‐type organic thermoelectrics. The excellent thermoelectric performance of n‐PT1 is due to its superior tolerance to doping. This work indicates that polythiophene derivatives without fused rings are low‐cost and high‐performance n‐type conjugated polymers.

The effect of ultraviolet irradiation on fluorinated graphene (FG) dispersed in toluene was investigated for the first time. The chemical and physical characteristics of FG before and after ultraviolet irradiation were analyzed by UV-vis, FTIR, XPS,EDS, oxygen flask combustion (OFC), XRD, TGA, Raman, SEM, TEM and fluorescence spectroscopy. It is found that the F/C ratio initially decreases rapidly and then slowly with irradiation time, finally to 0.179 after irradiation for 48 h. The nature of partial C-F bonds transforms from covalent to "semi-covalent" bonding in the process of irradiation. The restoration of new sp(2) clusters is fast at the early stage within 6 h of irradiation, promoting the structural rearrangement. The morphology of irradiated fluorinated graphene (iFG) is not significantly destroyed by ultraviolet while more overlapped sheets are formed due to quick defluorination. Photoluminescence (PL) properties show that "blue emission" located at 432 nm is enhanced due to the recovery of sp(2) domains. In particular, compared to non-aromatic solvents, there is a "synergistic effect" between aromatic solvents and ultraviolet in the defluorination process. FG is unstable and shows some structural transformations under ultraviolet irradiation, which can be used to tune its structure and properties.

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 ntype thermoelectric materials but also highlight a new strategy to develop n-type organic thermoelectric materials.

The intrinsic flexibility makes conjugated polymers an ideal choice for wearable thermoelectrics. The n-type polymer thermoelectric is still in its infancy. The majority of research on the n-type polymer thermoelectric focuses on the design of n-type conjugated polymers and high-efficiency n-dopants. In this paper, we report a self-standing and flexible nanofiber mat of an n-type conjugate polymer prepared with electrospinning technology. We choose a representative n-type conjugate polymer N2200. The electrospun N2200 nanofiber mat shows a maximal conductivity of 7.06 × 10–4 S/cm, a maximal Seebeck coefficient of −346 μV/K, and a maximal power factor of 0.0085 μW/(m K2). This thermoelectric performance is fairly comparable to that of the traditional spin-coated N2200 thin film. The nanofiber mat is self-standing, flexible, and stretchable and thus can attach to human skin and move with body movement. This work demonstrates the feasibility of fabricating flexible thermoelectric devices by an electrospinning technique and lays a foundation for the applications of n-type conjugated polymers in wearable electronics.

Organoboron polymers containing boron-nitrogen coordination bonds are a new type of n-type thermoelectric polymers. Their n-doping with a traditional hydride donor dopant suffers from low thermoelectric performance and unsatisfactory stability....