First‐Principles Study on Regulation Mechanism of Rare‐Earth Doping on Band Structure and Exciton Behavior of CeO ₂

To improve the photoresponse performance of CeO 2 ‐based abrasives for photocatalytic‐assisted chemical mechanical polishing (PCMP), the electronic structure, optical properties, carrier transport characteristics, and exciton binding energy of single‐doped Ce 0.75 RE 0.25 O 2 (RE = Y, La, Pr, Nd, Sm, Eu, and Yb) systems and double‐doped Ce 0.5 Eu 0.25 La 0.25 O 2 and Ce 0.5 Eu 0.25 Pr 0.25 O 2 systems were investigated using the first‐principles method based on density functional theory. The analysis of band structure and density of states revealed that rare‐earth doping can modulate band edge positions of CeO 2 , among which the bandgap of the Ce 0.75 La 0.25 O 2 system has the largest reduction, reaching 0.62 eV. The optical absorption spectra showed that the Y‐, Pr‐, Nd‐, Eu‐, and Yb‐doped systems all exhibited a red shift in the absorption edges, as well as enhanced absorption peaks in the visible and ultraviolet regions. Based on Boltzmann transport theory, the ratio of conductivity to relaxation time was analyzed, indicating that except for the Ce 0.75 La 0.25 O 2 system, Ce 0.75 RE 0.25 O 2 systems had better electronic transport performance for the n‐type doping. The exciton binding energy was analyzed using the G₀W₀ and Bethe–Salpeter methods, indicating that doping introduced the 4f localized states of RE and weakened electron–hole interactions. The electronic structure change of the Ce 0.5 Eu 0.25 La 0.25 O 2 system was reflected in the synergistic effect between band edge modulation and localized states of doped elements; whereas that of the Ce 0.5 Eu 0.25 Pr 0.25 O 2 system exhibited the redistribution of localized 4f states near the band edge. The light absorption capacity, carrier transport characteristics and exciton binding energy of two double‐doped systems were superior to those of the corresponding single‐doped systems.