Study On The Green Synthesis And Green Crystal Transformation Of TiOPc And Its Application

Oxotitanium phthalocyanine(TiOPc) is a widely used organic functional material. In the conventional synthesis methods, high-boiling organic solvents such as quinoline, tetralin, N-methylpyrrolidone, 1-chloronaphthalene and ortho-dichlorobenzene are used. These toxic solvents would produce chlorine or heterocyclic impurities, reducing the purity of TiOPc, increasing the difficulty of post-processing and causing security and environmental issues. The transformation of amorphous TiOPc using chlorobenzene, dichlorobenzene, chloronaphthalene and other halogen-containing organic solvents are also harmful to environment and human health.In this paper, polydimethylsiloxane(PDMS), dodecylbenzene and diphenyl methane were used as reaction solvent, tetrabutyl titanate and 1,3-diiminoisoindoline were used as raw materials for preparing oxotitanium phthalocyanine(TiOPc). The results showed that when using diphenyl methane as reaction solvent, the yeild of the product was the highest, and the post-processing was the easier than in the case of other solvents.The orthogonal experiment was applied to optimize the reaction conditions for preparing TiOPc in diphenyl methane. The optimal reaction conditions were reaction temperature 200 °C, reaction time 3 h, molar ratio of tetrabutyl titanate to 1,3-diiminoisoindoline 3.5: 1 and adding dropwise of tetrabutyl titanate in the reaction system at 120-130 °C. Under the above conditions, TiOPc was obtained in the yeild of 76.8%. The product was characterized by X-ray diffraction, infrared spectroscopy, ultraviolet-visible absorption spectrum, MALDI-TOF-MS spectrometry and elemental analysis. Enlargement experiments were carried out under the optimal conditions in a 5 L reactor and the average yeild of TiOPc was over 70%.Benzene, toluene, xylene, mesitylene, diphenyl methane, ethylbenzene, n-propyl benzene and dodecylbenzene were mixed with water to get crystal form adjustment solutions. Amorphous TiOPc would transformed to Y-TiOPc in the presence of some of these solutions. The effects of temperature and time of the crystal transformation were investigated. The obtained crystal was determined for its crystal form by measuring it for an X-ray diffraction spectrum. The analysis showed that alkyl aromatics with fewer substituents or shorter alkyl chain were helpful for the crystal transform. And the existence of benzene, toluene, xylene or ethylbenzene made might cause the formation of β-TiOPc because the adjustment solutions reduce the energy required for crystal transformation.Y-TiOPc obtained using toluene, xylene, mesitylene and ethylbenzene as crystal transformation solvents were used to fabricate organic photoconductors, and gave small residual potential(60～80 V) and decay rate of surface potential in dark(20～25 V/s), with excellent photoconductive sensitivity(0.12～0.14 μJ/cm~2).β-TiOPc was applied in perovskite solar cells as hole transporting material, with PCE 3.14%. α-TiOPc was applied in perovskite solar cells as light absorber material together with CH3NH3PbI3 and made JSC increased to 12.65 mA/cm~2 from 9.40 mA/cm~2.