Sb3+-doped terbium-based metal halide with efficient dual band emission for ratiometric temperature sensing

Low-dimensional organic-inorganic hybrid metal halides (HMH) have attracted widespread attention due to their tunable chemical composition and exceptional optoelectronic properties. However, there are only limited numbers of reports about lanthanide elements-based metal halides. Herein, we synthesize a zero-dimensional (0D) metal halide, (DFPD) 4 TbCl 7 (DFPD = 4,4-difluoropiperidinium), which exhibits intrinsic emission from the lanthanide ion (Tb 3+ ). Interestingly, by doping a small amount of Sb 3+ , an additional emission peak emerged at 625 nm. Apart from the dual band photoluminescence (PL), the photoluminescence quantum yield (PLQY) is increased from ~40% to near unity (99.6%) after doping (DFPD) 4 TbCl 7 HMH with Sb 3+ . To reveal the enhanced PLQY and dual band emission in (DFPD) 4 TbCl 7 :Sb 3+ , we carried out temperature-dependent PL measurements and density functional theory (DFT) calculation. We found the observed dual-band emission originated from intrinsic emission of Tb and self-trapped exciton (STEs) emission, which is introduced by the [SbCl 6 ] 3− octahedron. The extra radiative channel introduced by STEs contributes to the enhanced PLQY. Taking advantage of the efficient PL and high stability of (DFPD) 4 TbCl 7 :Sb 3+ , we fabricated a stable white-light-emitting diode with a color rendering index of 93. Furthermore, the temperature dependent PL of (DFPD) 4 TbCl 7 :Sb 3+ ensures its application as active material for optical thermometry. Our work provides a new strategy for developing lanthanide-based HMH with high performance for light emitting applications.