Synthesis and Characterization of Solution-Processable Ladderized n-Type Naphthalene Bisimide Copolymers for OFET Applications

Abstract

Solution-processable n-type ladder-based polymers are highly desirable due to their potential capability to form strong π–π interactions. A series of 5 highly soluble naphthalene diimide (NDI) polymers are presented, differing in the degree to which they are able to form imine-bridged ladder polymer structures. Average electron mobilities as high as 0.0026 cm2 V–1 s–1, which show an electron-mobility improvement of 4 orders of magnitude following ladderization, and on/off current ratios on the order of 104 are reported for the novel material PNDI-2BocL, an alkyl-substituted poly(benzoquinolinophenanthrolinedione). The structure–property relationship of the aforementioned series of copolymers is presented and discussed as it pertains to organic field-effect transistor (OFET) performance.

Fully conjugated ladder polymers

“…Luscombe and coworkers also reported solution processable imine-bridged ladder polymer 24 containing naphthalene diimide (NDI) building blocks, synthesized using the same method as 24 (Scheme 10). 17 The β-branched 2-octyldodecyl alkyl side chain on the NDI nitrogens provided sufficient solubility for ladder polymer 25 in common organic solvents. It is worthy to note that the SEC-measured molecular weight of 25 ( M n = 14 kg mol –1 ) was overestimated due to the increased hydrodynamic radius of the rigid, ribbon-like backbone, giving a higher M n than the precursor conjugated polymer (7.2 kg mol –1 ).…”

“…17 For example, in LPPPs 11 and 12 , the two alkyl groups installed on the quaternary sp 3 carbon center can be viewed as a branched alkyl group. As the branching point is moved farther from the polymer chain, interchain π–π distance decreases, leading to a general trend of decreasing solubility but increasing charge carrier mobility in bulk.…”

Imide- and Amide-Functionalized Polymer Semiconductors

“…Despite the high degree of backbone coplanarity, the moderate P63 μ e is likely due to its unfavorable LUMO (−3.54 eV), low M n (14 kDa), and amorphous film microstructure. 206 P64 containing phenothiazine was synthesized via Suzuki coupling. The band gap (1.4 eV) of P64 is smaller than that (1.5 eV) of the PDI polymer P6.…”

Strategies for the Synthesis of Functional Naphthalene Diimides

“…Strategy B was also applied to construct diagonally condensed, NDI-based ladder polymers, as shown by Luscombe and co-workers. [73] After a Stille coupling of 2,6-Br 2 -NDI with di-tert-butyl-(2,5-bis(tributyl- Figure 7. Structures of longitudinally extended naphthalene diimides.…”