DFT study of M-doped (M = P, As, Bi) VO2 for thermochromic energy-saving materials

Abstract

The group VA elements (P, As, Bi) doped VO2 were thoroughly investigated using the DFT calculations to evaluate the electronic properties, formation Helmholtz free energy, formation energy and the phase transition temperature (Tc). The calculated results showed that these atoms (M = P, As, Bi) could be easily doped at the octahedral interstitial site or in replacing of V or O atoms to reduce the Tc of VO2. All M-doped VO2 could narrow the band gap of Eg2 where the Eg2 value of Bi-doped VO2 was the smallest (about 0.30 eV). The Tc for Bi@i, Bi@V, and Bi@O could be reduced to 85, 159, 23 K for the model of one M atom doped in the octahedral interstitial site or in replacing of one V or O atom of VO2 supercells containing 32 V atoms and 64 O atoms, respectively. It means that the Bi-doped VO2 could be a better promising candidate to obtain good thermochromic energy-saving foils. These results will give the experimental researchers a new possibility to regulate the phase transition of VO2.