Intermediate excited state suppression and upconversion enhancement of Er3+ ions by carbon-doping boosting photocarrier separation in bismuth oxychloride nanosheets

Jiajun Han; Taizhong Xiao; Jiajing Wang; Tong Liu; YongJin Li; Yuehong Peng; Zhaoyi Yin; Jianbei Qiu; Zhengwen Yang; Zhiguo Song

doi:10.1016/j.jcis.2020.11.120

Intermediate excited state suppression and upconversion enhancement of Er³⁺ ions by carbon-doping boosting photocarrier separation in bismuth oxychloride nanosheets

J Colloid Interface Sci. 2021 Apr 15:588:838-846. doi: 10.1016/j.jcis.2020.11.120. Epub 2020 Dec 2.

Authors

Affiliations

¹ School of Materials Science and Engineering, Kunming University of Science and Technology, Kunming 650093, China.
² School of Materials Science and Engineering, Kunming University of Science and Technology, Kunming 650093, China. Electronic address: liyongjin@kust.edu.cn.
³ School of Materials Science and Engineering, Kunming University of Science and Technology, Kunming 650093, China. Electronic address: qiu@kmust.edu.cn.
⁴ School of Materials Science and Engineering, Kunming University of Science and Technology, Kunming 650093, China. Electronic address: songzg@kmust.edu.cn.

PMID: 33309147
DOI: 10.1016/j.jcis.2020.11.120

Abstract

Low luminescence efficiency of rare-earth ions dopedupconversion (UC) nanomaterials is still a major limitation for their applications.Here, based on bismuth oxychloride nanosheets that show efficient photocarriers separation due to combining spontaneous polarization and layered semiconductor, we report a new carbon heterovalent doping strategy for efficient UC luminescence enhancement by suppressing the intermediate excited states of Er³⁺ ions. The first-principles calculations and photoelectrochemical characterizations provide evidences that the replacement of C ions for Cl strengthen the spontaneous polarization and inter electric field (IEF) of bismuth oxychloride nanosheets, which further improve the photocarriers separation efficiency. Under 808 or 980 nm excitation, the emission intensity of ⁴I_13/2 energy level of Er³⁺ ions (1550 nm) increase slightly with C doping, but the its decay time and the visible UC emission are improved tremendously at the same time. We show that the recombination rate of intermediate excited state electrons of Er³⁺ ions with the ground state is inhibited by the enhanced IEF, which promotes the energy reabsorption transition to upper energy levels, thus enhancing the visible UC emission. This work not only may provide a new insight into the method for engineering of UC emissions but also deepen the understanding for layered semiconducting material to modify the transition of Lanthanide ions.

Keywords: Inter electric field; Layered semiconductor; Photocarrier separation; Rare earth ions; Upconversion enhancement.