Defect States-Related Photothermal Conversion of UV Photons in TiO<sub>2</sub>-Based Materials
Xin Hu, Shengyang Wang, Jun Li, Zhaochi Feng, E. H. Wang, Can Li
Abstract
Conversion of solar spectrum to heat has attracted widespread attentions. However, the efficient transformation of light in the ultraviolet region to heat is a great challenge. UV light-responsive TiO 2 is herein studied for the photothermal conversion process. We found that N-doped TiO 2 can show an increased photothermal internal conversion efficiency from 65% for TiO 2 to 82% for N-TiO 2 in the UV range. Hall tests ( N T, trap density) and DFT simulations ( E T, trap position) revealed that the defect density of deep-level defect states is greatly increased upon N doping. Accordingly, it is deduced that the photo-to-thermal process occurs through a defect-related nonradiative transition, and its efficiency (η) is strongly correlated with the defect states density ( N T ) and defect energy states ( E T ). Furthermore, this understanding of defect-correlated photothermal conversion could extend to other nonmetallic dopant systems (i.e., S dopants and the O vacancy).