Organic doping-tailored crystal fields and triplet excitons in Tb3+ complex scintillators for high-sensitivity X-ray detection

Lanthanide complex crystals represent an important class of scintillation materials; however, their radioluminescence performance remains limited due to a lack of versatile strategies for precise regulation. Here, we develop an organic doping strategy and synthesize a Tb complex (Tb-BDC-OAc) crystal of Tb 3+ coordinated with 1,4-dicarboxybenzene (H 2 BDC) and acetic acid (dopant, OAc - ). After systematic optimization, the Tb-BDC-OAc₂ crystal achieves a photoluminescence quantum yield (PLQY) of up to 96.4 % under 330 nm excitation, which we attribute to improved triplet exciton dynamics that enhance ligand-to-Tb 3+ energy transfer. In contrast, excitation at 368 nm—directly targeting Tb 3+ —yields an even greater PLQY enhancement of 19.1 %, driven by crystal-field perturbation tuning via OAc - doping. This dual mechanism synergistically increases the light yield to 19400 photons MeV −1 while maintaining exceptional stability (99.8 % light yield retention after 30 days in ambient conditions). The crystal’s tailored energy-level alignment and suppressed afterglow (<1 s decay) enable ultrasensitive X-ray detection with a record-low limit of 15.77 nGy s −1 . By decoupling triplet exciton regulation (330 nm excitation) from crystal-field engineering (368/377 nm excitation), this work establishes a paradigm for designing high-efficiency, low-cost scintillators for biomedical imaging and radiation monitoring.