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

Two-dimensional conjugated polymers (2DCPs), composed of multiple strands of linear conjugated polymers with extended in-plane pi-conjugation, are emerging crystalline semiconducting polymers for organic (opto)electronics. They are represented by two-dimensional pi-conjugated covalent organic frameworks, which typically suffer from poor pi-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 similar to 1.3 eV with highly delocalized pi-electrons. Density functional theory calculations unveil strongly dispersive energy bands with small electron-hole reduced effective masses of similar to 0.15m(0) 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 similar to 970 cm(2) 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.

Automated summary

This study overcomes the low charge carrier mobility issue of two-dimensional conjugated polymers (2DCPs) by synthesizing two semiconducting 2DCPs (2DCP-MPc, with M = Cu or Ni) with high mobility. The 2DCP-MPcs exhibit highly dispersive energy bands and small electron-hole effective masses, and demonstrate exceptionally high electron and hole mobilities at room temperature, surpassing those of 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.