Exceptionally high charge mobility in phthalocyanine-based poly(benzimidazobenzophenanthroline)-ladder-type two-dimensional conjugated polymers

Abstract

Two-dimensional conjugated polymers (2DCPs), composed of multiple strands of linear conjugated polymers with extended in-plane π-conjugation, are emerging crystalline semiconducting polymers for organic (opto)electronics. They are represented by two-dimensional π-conjugated covalent organic frameworks, which typically suffer from poor π-conjugation and thus low charge carrier mobilities. Here we overcome this limitation by demonstrating two semiconducting phthalocyanine-based poly(benzimidazobenzophenanthroline)-ladder-type 2DCPs (2DCP-MPc, with M = Cu or Ni), which are constructed from octaaminophthalocyaninato metal(ii) and naphthalenetetracarboxylic dianhydride by polycondensation under solvothermal conditions. The 2DCP-MPcs exhibit optical bandgaps of ~1.3 eV with highly delocalized π-electrons. Density functional theory calculations unveil strongly dispersive energy bands with small electron–hole reduced effective masses of ~0.15m0 for the layer-stacked 2DCP-MPcs. Terahertz spectroscopy reveals the band transport of Drude-type free carriers in 2DCP-MPcs with exceptionally high sum mobility of electrons and holes of ~970 cm2 V−1 s−1 at room temperature, surpassing that of the reported linear conjugated polymers and 2DCPs. This work highlights the critical role of effective conjugation in enhancing the charge transport properties of 2DCPs and the great potential of high-mobility 2DCPs for future (opto)electronics.

Construction of Thiadiazole-Bridged sp2-Carbon-Conjugated Covalent Organic Frameworks with Diminished Excitation Binding Energy Toward Superior Photocatalysis

“…The effective mass of electrons for sp 2 c-COF-ST was calculated to be 0.495 m e , which was smaller than mix-COF-SNT (0.703 m e ) and imi-COF-SNNT (6.395 m e ), further indicating that the −C�C− linkage was more conducive for carrier migration than the − C�N− linkage (Figures S30−32 and Table S7). 58 The PL intensity of the three COFs decreased as the temperature rose (Figure 5a,c,e), mainly due to thermally activated nonradiative recombination processes. 59 The binding energy of excitons can be further estimated by combining integrated PL intensity and temperature in the following equation…”

“…The effective mass of electrons for sp 2 c-COF-ST was calculated to be 0.495 m e , which was smaller than mix-COF-SNT (0.703 m e ) and imi-COF-SNNT (6.395 m e ), further indicating that the –CC– linkage was more conducive for carrier migration than the –CN– linkage (Figures S30–32 and Table S7). The PL intensity of the three COFs decreased as the temperature rose (Figure a,c,e), mainly due to thermally activated nonradiative recombination processes . The binding energy of excitons can be further estimated by combining integrated PL intensity and temperature in the following equation I ( T ) = I 0 1 + A e − E b / k B T where I 0 is PL intensity at 0 K, A is the proportional constant, k B is the Boltzmann constant, and E b is the binding energy. , The exciton binding energies of sp 2 c-COF-ST, mix-COF-SNT, and imi-COF-SNNT were determined by fitting the experimental data to be 30.7, 46.3, and 56.6 meV, respectively (Figure b,d,f), which is consistent with the changing trend of DFT calculations for representative fragments (Figure S33).…”

Unique Octupolar 2D‐Polymer Frameworks as Mixed Conductors and Metal‐Free Catalysts for Dual‐Promoted Li and S Electrochemistry: Multi‐regulation Role of Ethoxylation Chemistry

“…Actually, our 2D-framework belongs to a kind of new covalent organic framework material (COF) and is also called as 2D COF, according to literatures. [12] Here, all three materials comprise interconnected D3-(A core) octupolar units with the same acceptor cores whist Cyano-OCF-EO and Cyano-OCP-EO bear stronger electron donor with respect to Cyano-OCP. As described previously, [13] a D3-(A core) octupolar structure, as a kind of three-branched polar structure, consists of three dipolar subunits connected via a central A core.…”

“…The synthetic route of cyano‐vinylene‐linked octupolar 2D‐conjugated polymer frameworks grafted with triethoxylate chains (−(CH 2 CH 2 O) 3 H) (namely Cyano‐OCF‐EO) and amorphous octupolar polymer counterparts with and without triethoxylate substitutes (namely Cyano‐OCP‐EO and Cyano‐OCP) is illustrated in Scheme S1–2 and Figure 1a. Actually, our 2D‐ framework belongs to a kind of new covalent organic framework material (COF) and is also called as 2D COF, according to literatures [12] . Here, all three materials comprise interconnected D3‐(A core) octupolar units with the same acceptor cores whist Cyano‐OCF‐EO and Cyano‐OCP‐EO bear stronger electron donor with respect to Cyano‐OCP.…”

Poly(benzimidazobenzophenanthroline)‐Ladder‐Type Two‐Dimensional Conjugated Covalent Organic Framework for Fast Proton Storage**

“…Two‐dimensional conjugated covalent organic frameworks (2D c ‐COFs) [19–22] represent an emerging class of layer‐stacked, crystalline 2D conjugated polymers (2D CPs) with defined porosity, [23] active sites, [24] tailorable electro‐activity, [25] and high charge carrier mobility, [26–29] which are promising candidates for electronic [28] and electrochemical [30–33] applications. In particular, the incorporation of redox‐active units would confer unique redox behavior to the resultant 2D c ‐COFs [34–37] .…”