Inside-out Ostwald ripening： A facile process towards synthesizing anatase TiO2 microspheres for high- efficiency dye-sensitized solar cells  

作　　者：Yong Ding Xin Xia Wangchao Chen Linhua Hu Li'e Mo Yang Huang Songyuan Dai 

机构地区：[1]Beijing Key Laboratory of Novel Thin-Film Solar Cells, North China Electric Power University, Beijing 102205, China [2]Key Laboratory of Novel Thin-film Solar Cells, Institute of Applied Technology, Hefei Institutes of Physical Science, Chinese Academy ot Sciences, Hefei 230031, China

出　　处：《Nano Research》2016年第7期1891-1903,共13页纳米研究（英文版）

基　　金：We acknowledge the Steady High Magnetic Field Facility in High Magnetic Field Laboratory, Chinese Academy of Sciences for the EPR measurement. This work was supported by the National Natural Science Foundation of China （Nos. 21173228 and 61204075）, and the National High-Tech Research and Development Program of China （No. 2015AA050602）.

摘　　要：A facile inside-out Ostwald ripening route to the morphology-controlled preparation of TiO2 microspheres is developed. Here, TiO2 hollow microspheres （HM） and solid microspheres （SM） are prepared by adjusting the volume ratio of isopropanol （IPA） to acetylacetone （Acac） in the solvothermal process. During the formation process of HM, precipitation of solid cores, subsequent deposition of outer shells on the surface of cores, and simultaneous core dissolution and shell recrystallizafion are observed, which validate the inside-out Ostwald ripening mechanism. Design and optimization of the properties （pore size, surface area, and trap state） of TiO2 microspheres are vital to the high performance of dye- sensitized solar cells （DSSCs）. The optimized TiO2 rnicrospheres （rHM and rSM） obtained by post-processing on recrystallization, possess large pore sizes, high surface areas and reduced trap states （Ti3~ and oxygen vacancy）, and are thus ideal materials for photovoltaic devices. The power conversion efficiency of DSSCs fabricated using rHM photoanode is 11.22%, which is significantly improved compared with the 10.54% efficiency of the rSM-based DSSC. Our work provides a strategy for synthesizing TiO2 microspheres that simultaneously accommodate different physical properties, in terms of surface area, crystallinity, morphology, and mesoporosity.A facile inside-out Ostwald ripening route to the morphology-controlled preparation of TiO2 microspheres is developed. Here, TiO2 hollow microspheres （HM） and solid microspheres （SM） are prepared by adjusting the volume ratio of isopropanol （IPA） to acetylacetone （Acac） in the solvothermal process. During the formation process of HM, precipitation of solid cores, subsequent deposition of outer shells on the surface of cores, and simultaneous core dissolution and shell recrystallizafion are observed, which validate the inside-out Ostwald ripening mechanism. Design and optimization of the properties （pore size, surface area, and trap state） of TiO2 microspheres are vital to the high performance of dye- sensitized solar cells （DSSCs）. The optimized TiO2 rnicrospheres （rHM and rSM） obtained by post-processing on recrystallization, possess large pore sizes, high surface areas and reduced trap states （Ti3~ and oxygen vacancy）, and are thus ideal materials for photovoltaic devices. The power conversion efficiency of DSSCs fabricated using rHM photoanode is 11.22%, which is significantly improved compared with the 10.54% efficiency of the rSM-based DSSC. Our work provides a strategy for synthesizing TiO2 microspheres that simultaneously accommodate different physical properties, in terms of surface area, crystallinity, morphology, and mesoporosity.

关 键 词：Ostwald ripening dye-sensitized solar cell TiO2 microsphere hollow structure ACETYLACETONE 

分 类 号：TQ342.81[化学工程—化纤工业] TM914.4[电气工程—电力电子与电力传动]