Red–NIR Luminescence in Rare-Earth and Manganese Ions Codoped Cs<sub>4</sub>CdBi<sub>2</sub>Cl<sub>12</sub> Vacancy-Ordered Quadruple Perovskites
Peipei Dang, Guodong Zhang, Wei Yang, Hongzhou Lian, Guogang Li, Jun Lin
Abstract
Combining rare-earth ions (RE 3+ ) in halide perovskites is a hopeful strategy to produce interesting optical properties in visible and near-infrared (NIR) regions. Here, RE 3+ (RE: Nd, Ho, Er, Tm) ions are successfully introduced into Cs 4 Cd 1– w Mn w Bi 2 Cl 12 (0 ≤ w ≤ 1) vacancy-ordered quadruple perovskites through a facile hydrothermal method. In addition to the strong orange-red Mn 2+ emission, the as-prepared materials exhibit the effective characteristic emission of RE 3+ in the red and NIR regions via constructing a Mn 2+ energy bridge. With Mn 2+ gradually replacing Cd 2+ in Cs 4 Cd 1– w Mn w Bi 2 Cl 12:RE 3+, the photoluminescence (PL) of RE 3+ in the red and NIR ranges shows an increasing trend until it reaches the strongest value ( w = 1). The energy transfer processes of [BiCl 6 ] 3– → Mn 2+ → RE 3+ are confirmed, and the corresponding mechanism is explored. According to the manipulation of the Mn 2+ /Cd 2+ component, an evolution process from direct to indirect band gaps is verified via a combined experimental–theoretical approach. White light-emitting diodes (LEDs) are fabricated by employing Ho 3+ -doped Cs 4 MnBi 2 Cl 12 on near-ultraviolet (n-UV) LED chips, achieving an improved color rendering index (CRI) from 83.3 to 93.0 compared to that of the parent compound. Codoping RE 3+ (RE: Nd, Ho, Er, Tm) ions into Cs 4 MnBi 2 Cl 12 results in an ultrawide emission covering both NIR I and NIR II regions, implying a great potential for NIR detection application.