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Decreased domain size of p-DTS(FBTTh 2) 2/P(NDI2OD-T2) blend films due to their different solution aggregation behavior at different temperatures

Ke Zhou, Qiaoqiao Zhao, Rui Zhang, Xinxiu Cao, Xinhong Yu, Jiangang Liu, Yanchun Han

Phys Chem Chem Phys. 2017 Dec 13;19(48):32373-32380.

PMID: 29184937

Abstract:

Nanoscale interpenetrating networks play a key role in determining the optoelectrical properties of functional blends. However, phase separated large domain sizes could probably be observed in pristine films composed of two crystalline components. For example, p-DTS(FBTTh2)2/P(NDI2OD-T2) 3/2 blend films with interpenetrating networks are obtained, however, large domain sizes are found when they are prepared from a 20 °C solution due to the simultaneous process of crystallization and phase separation during solvent evaporation. In this paper, we proposed to reduce the domain size of p-DTS(FBTTh2)2/P(NDI2OD-T2) blend films using their different solution aggregation behaviors at different temperatures. The aggregation of p-DTS(FBTTh2)2 molecules in chlorobenzene (CB) was insensitive to the solution temperature. However, the in situ absorption spectra of the neat P(NDI2OD-T2) solution from 80 °C to room temperature indicated that P(NDI2OD-T2) aggregation increased with decreasing temperature due to intrachain interactions. Therefore, in order to reduce the domain size, we employed a hot solution to prepare the blend films. During the solidification process, the majority of p-DTS(FBTTh2)2 molecules were confined in the P(NDI2OD-T2) networks prior to occurrence of severe p-DTS(FBTTh2)2 aggregation. Thus, the domain size of the p-DTS(FBTTh2)2 phase became smaller than that of the pristine films, leading to a decrease in the corresponding photoluminescence intensity of the blend films. In addition, the crystallinity of the blend films improved after thermal annealing, which resulted from the ordered alignment of p-DTS(FBTTh2)2 molecules facilitated by their enhanced diffusion ability. Based on the various morphologies, a possible phase diagram of the p-DTS(FBTTh2)2/P(NDI2OD-T2) blend system was depicted, which could be a guide to directly control the morphology of blend films.

Chemicals Related in the Paper:

Catalog Number Product Name Structure CAS Number Price
AP1100243400 P(NDI2OD-T2) P(NDI2OD-T2) 1100243-40-0 Price
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