The role of epitaxial strain on photoconductive performance in LaNiO3 epitaxial thin films

In this work, LaNiO 3 epitaxial thin films on (001) single-crystal LaAlO 3 and SrTiO 3 substrates were deposited by polymer assisted deposition method, respectively. Additionally, LaNiO 3 polycrystalline film was coated on ceramic substrate using LaNiO 3 powder obtained from precursor solution in polymer assisted deposition. Due to the difference of lattice mismatch between LaNiO 3 and single-crystal substrates, LaNiO 3 thin films suffer different epitaxial strain, resulting in distortion of NiO 6 octahedrons which increases with the intensity of strain. Such phenomena lead to the decrease of the field splitting energy of NiO 6 octahedron and the band gap value of LaNiO 3 , further increasing the charge transition and enhancing the visible-light photoconductivity . The existence of epitaxial strain brings more Ni 2+ and adsorbed oxygen into perovskite type LaNiO 3 , introduces more oxygen vacancy defects, reduces the complex rate of photo induced electron-hole pairs, and thereby improves the photoelectric activity of LaNiO 3 . This work provides a feasible method to control the structure distortion and photoconductivity effect of all-inorganic perovskite.