Abstract
Since the advent of graphene, the development of crystalline two-dimensional (2D) organic materials with semiconducting features has been extensively explored for their potential optoelectronic applications. Despite extensive progress in this field, it is still challenging to realize laterally extended organic materials with high electrical transport properties. Here, we report a 2D ladder-type fused aromatic network (FAN) in which backbones are composed of hydrophenazine (HP) linkage (designated HP-FAN). Consequently, its 2D extended delocalization of π-molecular orbitals imparts a semiconducting band gap and facilitates fast intra-chain charge transport. The as-prepared HP-FAN exhibits semiconducting features with calculated and experimental band gaps of approximately 1.44 and 1.54 eV, respectively, with an unusual flat band. The HP-FAN thin flakes, isolated by polydimethylsiloxane stamping, exhibit remarkable performance in a p-type field-effect transistor (FET) and a Hall effect device. Given its laterally extended ladder-type π-conjugated structure, the HP-FAN has extensive potential for applications in thin-film optoelectronic devices.
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•A ladder-type hydrophenazine-linked 2D fused aromatic network (HP-FAN) was realized•The HP-FAN has an inherent semiconducting band gap along with a parallel flat band•The HP-FAN has high intrinsic electrical conductivity without doping•The HP-FAN exhibits a remarkable performance in electronic devices with high mobility
The zero band gap of graphene has been a critical roadblock for organic electronic devices. Hence, the development of promising semiconducting 2D organic materials has been extensively explored for the past few decades. 2D polymers (2DPs) with unique electronic features have emerged as a significant alternative to holey graphene. Here, we employed an irreversible ladderization reaction into a 2DP, realizing a laterally extended ladder-type fused aromatic network (HP-FAN). The ladder-type fused aromatic structures endow the HP-FAN with extended delocalized π-molecular orbitals, facilitating fast intra-chain charge transport. Consequently, the HP-FAN exhibits a semiconducting band gap with a unique flat band. In addition, the HP-FAN thin flakes, isolated by polydimethylsiloxane stamping, demonstrate remarkable performances as electronic devices with high charge carrier transport. Overall, these findings provide a significant leap in the design and further advance in semiconducting 2D polymers.
2D polymers (2DPs) with unique electronic features have emerged as significant alternative materials to holey graphene. As a promising 2DP, a hydrophenazine (HP)-linked highly crystalline 2D ladder-type fused aromatic network (FAN) has been realized for the first time. Without chemical doping, the HP-FAN has an inherent semiconducting band gap along with an unusual flat parallel band. Its organic field-effect transistors and Hall effect devices show outstanding charge carrier mobilities and high on-off ratios.