Energy Band-Gap Engineering of Conjugated Microporous Polymers via Acidity-Dependent In-situ Cyclization
Journal of the American Chemical Society | 10 Aug 2018
J Lee, O Buyukcakir, TW Kwon and A Coskun
Conjugated microporous polymers (CMPs) attracted a great deal of attention in recent years owing to their unique structure integrating π-electronic delocalized backbone into a porous network for the simultaneous transport of charges and materials. However, tuning electronic properties of CMPs so far has been limited to an approach of varying the monomers, and the precious metal catalysts are inevitably needed for the C-C coupling reaction. Here, we present a powerful strategy to synthesize CMPs and precisely tune their optical band gap and surface area through metal-free in-situ cyclization reaction controlled by the acid strength of acid catalysts. Notably, the optical band gap of CMPs showed a linear relationship with the pKa of acid catalysts, which provides us with the ability to obtain the desired band gap between 2.07 - 3.35 eV, falling in the range of the visible solar spectrum. Moreover, CMPs exhibited excellent textural properties such as microporosity and high specific surface area (up to 806 m2g-1).
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