Rational Optimization of Benzo[2,1‐b;3,4‐b′]dithiophene‐Containing Polymers for Organic Field‐Effect Transistors

A Polymer with a Benzo[2,1‐b;3,4‐b′]dithiophene Moiety for Photovoltaic Applications

“…Thus, this polymer demonstrates high charge-carrier mobilities up to 0.5 cm 2 V À1 s À1 on plastic substrates. [11] As shown in Figure 1 b, an absorption maximum of PBTT occurs at 540 nm in a dichlorobenzene solution, while a PBTT film exhibits a broader absorption. In addition, the absorption of the solution mixture of PBTT and [6,6]-phenyl-C 71 -butyric acid methyl ester ([70]PCBM) overlaps with nearly the whole visible region from 350 to 650 nm, which renders the blend as a good light absorber for highly efficient photovoltaic devices.…”

High‐Mobility Conjugated Polymers Based on Fused‐Thiophene Building Blocks

“…This increases the ionization potential of the polymer and is thus expected to improve air stability under operation. [33] Additionally, compared to a single thiophene ring, it must be pointed out that due to the large resonance stabilization energy of BDT, the delocalization of electrons from the BDT unit into the backbone is less favorable than from the thiophene ring. As a result, a more sable copolymer with high performance can be obtained by using BDT as the core unit.…”

“…[34] Compared with 4b, thin films based on the homopolymer of benzo[2,1-b:3,4-b 0 ]dithiophene (4a, Figure 4) exhibited a low degree of ordering with a large value of p-p staking distance (4.3 Å ), which reduced charge carrier mobility by two orders of magnitude. [33] The linear polymer 4d (Figure 4) exhibits chargecarrier mobilities of one order of magnitude lower than the curved counterpart 4c (Figure 4). [33] This is surprising if comparing the almost identical X-ray scattering patterns of both polymers.…”

“…[33] The linear polymer 4d (Figure 4) exhibits chargecarrier mobilities of one order of magnitude lower than the curved counterpart 4c (Figure 4). [33] This is surprising if comparing the almost identical X-ray scattering patterns of both polymers. The curvature of 4c guarantees an optimum compromise between solubility and aggregation tendency to drive quick formation of highly ordered spin-coated polymer films.…”

“…Furthermore, FETs based on 4c manufactured on flexible substrate exhibited even higher charge carrier mobility of 0.5 cm 2 Á V À1 Á s À1 when the source-gate voltage is increased to 60 V, demonstrating its great potential for industrial application. [33] Incorporation of bi-3-methylthiophene into backbone of 4b leads to 100 nm red shift of absorption maximum of the roomtemperature solution of 4b (Table 4), suggesting a greater p-conjugation and substantially more ordered structure in 4e. [34] The distance between the neighboring dodecyl chains in 4e is about 16 Å , much larger than that of 4b (8.5 Å ), thus permitting a closer intermolecular chain packing.…”