A Low-Bandgap Conjugated Polymer Based on Squaraine with Strong Two-Photon Absorption

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• 作者：Qinqin Shi ; Wei-Qiang Chen ; Junfeng Xiang ; Xuan-Ming Duan ; Xiaowei Zhan
• 刊名：Macromolecules
• 出版年：2011
• 出版时间：May 24, 2011
• 年：2011
• 卷：44
• 期：10
• 页码：3759-3765
• 全文大小：892K
• 年卷期：v.44,no.10(May 24, 2011)
• ISSN：1520-5835

文摘

A new low-bandgap 蟺-conjugated D鈥揂 copolymer of squaraine and pyridopyrazine (P1) and a new small molecule squaraine鈥損yridopyrazine model compound (P2) were synthesized and compared. P1 and P2 exhibit strong NIR absorption and low bandgap (1鈥?.3 eV). P2 in solution shows an intense and sharp absorption peak at 764 nm, while P1 in solution exhibits a red-shifted and broad absorption peak at 808 nm. The HOMO and LUMO levels of P1 were estimated to be 鈭?.02 and 鈭?.15 eV, while the HOMO and LUMO levels of P2 were estimated to be 鈭?.27 and 鈭?.22 eV, respectively. Polymer P1 exhibits strong two-photon absorption (2PA) at telecommunication wavelengths with 2PA cross sections per repeat unit as high as 2300 GM, 3鈥? times that for the small molecule P2. The higher HOMO, the lower LUMO levels, lower bandgap, red-shifted absorption, and stronger two-photon absorption of P1 are attributed to higher degree of conjugation and delocalization of 蟺-electrons in the polymer.