新型窄带隙聚方酸菁的合成与光电性质

为了寻找更好的聚合物太阳能电池材料,我们首先通过Leimgruber-Batho法合成了苯并双吡咯M1及其正丁基取代的衍生物M1a,并以它们为给电子性单体,分别与吸电子性单体方酸交替共聚得到聚合物P1和P1a。用TGA、GPC表征聚合物的热稳定性和分子量,并通过紫外-可见光吸收光谱、循环伏安法研究了它们的光电性能。结果表明,两种聚合物分解温度均高于300℃,其中P1a的紫外-可见光最大吸收峰出现在597nm,带隙为1.73eV,而且其LUMO能级为-3.85eV,与最常用的有机n型材料PCBM的HOMO能级相当(-3.91eV),有可能在聚合物太阳能电池中得到应用。

Synthesis and Photoelectronic Properties of New Low-band-gap Polysquaraines

To explore better materials for polymer solar cells,benzodipyrrole(M1) and its derivative with n-butyl side groups(M1a) were synthesized by the Leimgruber-Batcho procedure.Then,two new low-band-gap polysquaraines,P1 and P1a were prepared via alternating copolymerization of the electron-accepting monomer(squaraine) with the electron-donating M1 and M1a,respectively.Thermal stability and molecular weights of the obtained polysquaraines were characterized by thermogravimetric analysis(TGA) and gel-permeation chromatography(GPC),and their photoelectronic properties were investigated by ultraviolet-visible(UV-Vis) absorption spectroscopy and cyclic voltammetry.It is found that both P1 and P1a show their decomposition temperatures over 300℃,in particular,P1a exhibits a maximum absorption peak centered at 597 nm and a band-gap of 1.73eV.Furthermore,the lowest unoccupied molecular orbital(LUMO) level of P1a is-3.85eV,which is close to that of the most commonly used organic n-type material,6,6-phenyl C61-butyric acid methyl ester(PCBM)(-3.91eV),suggesting that polysquaraine is a kind of promising material potentially applicable in polymer solar cells.