Pressure Effects on the Optoelectronic Property of\nNanocrystalline Anatase with Different Sizes

In\nthis study, we investigated the photoelectric properties of\nnanosized anatase (∼55 and ∼4 nm) under high pressure,\nutilizing in situ Raman spectroscopy, photocurrent measurements, and\ntheoretical calculations up to 27.6(5) GPa. Our findings reveal that\n55 nm anatase shows a significant photocurrent increase of 2.4 times\ncompared to ambient conditions before transitioning to the columbite\nphase at around 5.5(1) GPa. After this transition, the photocurrent\ngradually decreased up to 19.8(4) GPa. Notably, the columbite phase\nexhibited superior optoelectronic performance compared to the baddeleyite\nphase observed at approximately 15.5(3) GPa. For ∼4 nm anatase,\nan exceptional photocurrent increase of approximately 131 times was\nobserved at 5.4(1) GPa compared to 1.5(0) GPa, with only a slight\ndecrease between 5.4(1) and 27.6(5) GPa, and maintained a high level\neven after pressure release. The observed variations in photocurrent\nare attributed to changes in resistance, band gap, and absorption\ncoefficient, each influencing the material’s response differently\nacross various pressure ranges. These results underscore the potential\nof pressure-induced modulation to dramatically enhance the photoelectric\nproperties of nanosized anatase, especially in ∼4 nm anatase.\nThe ability to control the crystal structure and UV light response\nthrough pressure offers a promising strategy for improving the performance\nof TiO<sub>2</sub>-based ultraviolet photodetectors, making them more\neffective for advanced photoelectric applications.