Radially oriented mesoporous TiO₂ microspheres with single-crystal-like anatase walls for high-efficiency optoelectronic devices

Highly crystalline mesoporous materials with oriented configurations are in demand for high-performance energy conversion devices. We report a simple evaporation-driven oriented assembly method to synthesize three-dimensional open mesoporous TiO₂ microspheres with a diameter of ∼800 nm, well-controlled radially oriented hexagonal mesochannels, and crystalline anatase walls. The mesoporous TiO₂ spheres have a large accessible surface area (112 m²/g), a large pore volume (0.164 cm³/g), and highly single-crystal-like anatase walls with dominant (101) exposed facets, making them ideal for conducting mesoscopic photoanode films. Dye-sensitized solar cells (DSSCs) based on the mesoporous TiO₂ microspheres and commercial dye N719 have a photoelectric conversion efficiency of up to 12.1%. This evaporation-driven approach can create opportunities for tailoring the orientation of inorganic building blocks in the assembly of various mesoporous materials.