Influence of Solubilizing Group Removal Rate on the Morphology and Crystallinity of a Diketopyrrolopyrrole-Based Compound

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• 作者：Shabi Thankaraj Salammal ; Jean-Yves Balandier ; Saroj Kumar ; Erik Goormaghtigh ; Yves Henri Geerts
• 刊名：Crystal Growth & Design
• 出版年：2014
• 出版时间：January 2, 2014
• 年：2014
• 卷：14
• 期：1
• 页码：339-349
• 全文大小：770K
• ISSN：1528-7505

文摘

Thermally cleavable solubilizing groups have been introduced on a 蟺-conjugated core, which can be cleaved and volatilized via heat treatment directly after the thin film fabrication. The X-ray and atomic force microscopic investigations of 鈥?,6-di(2,2鈥?bithiophen-5-yl)pyrrolo[3,4-c]pyrrole-1,4-(2H,5H)-dione鈥?(DPP-4T) synthesized from its precursor (di-tert-butyl-3,6-di(2,2鈥?bithiophen-5-yl)-1,4-dioxopyrrolo[3,4-c]pyrrole-2,5-(1H,4H)-dicarboxylate) through thermal conversion reveals that the solubilizing group removal rate plays a crucial role on the ultimate grain size and crystallinity of the final compound (DPP-4T). This means that, when the heating rate is decreased from 50 to 0.1 掳C/min, the crystallinity of DPP-4T powder decreases from 49% to 34%, and the grain size of DPP-4T film reduces from 976 to 344 nm. The crystallite size of the films can be further reduced to 185 nm by decarboxylating the films isothermally at 120 掳C. The Fourier transform infrared spectra reveals that the reduction of crystallinity with the heating rate could be attributed to the trapping of gaseous byproducts inside the lattice, during the decarboxylation of the solubilizing group. The increment in intermolecular N鈥揌路路路O鈺怌 hydrogen bond length together with the trapped gaseous byproducts results in a blue shift in the UV鈥搗is absorption spectra while decreasing the heating rate as well as the isothermal decarboxylation temperature.