Theory‐Guided Defect Tuning through Topochemical Reactions for Accelerated Discovery of UVC Persistent Phosphors

Abstract

Long persistent phosphors (LPPs) have attracted enduring attention owing to their wide applications. However, the discovery of LPPs is thus far largely the results of trial and error. Here, theory‐guided defect tuning through topochemical reactions is demonstrated for accelerated discovery of emerging LPPs. First‐principles calculations are employed to identify the thermodynamic charge‐transition levels of different defect states, which help examine whether the candidate structure is a suitable host for afterglow. Rationally tuning the species and concentrations of defects through topochemical reactions is then illustrated, which leads to discovery of Pr3+‐doped LaPO4 featuring ultraviolet C afterglow with a lasting time of over 2 h. Such a strategy, in conjunction with advanced characterizations including high‐resolution synchrotron X‐ray diffraction, positron annihilation lifetime spectroscopy, and electron spin resonance, suggests a radical‐involved afterglow mechanism. Importantly, it is illustrated that this concept can be extended for the discovery of more LPPs. It is suggested that theory‐guided defect engineering enabled by topochemical reactions can be used as a powerful tool to accelerate discovery of novel LPPs with much clearer afterglow mechanisms, with implications even for the design of other optoelectronic materials.

First-Principles Study on Self-Activated Luminescence and 4f → 5d Transitions of Ce3+ in M5(PO4)3X (M = Sr, Ba; X = Cl, Br)

“…During the preparation, the native defects are ineluctably generated in the samples. It is significantly important to understand the geometric, thermodynamic, electronic, and luminescent properties of the native defects, since they play a non-negligible (beneficial − or harmful , ) role in the luminescence of phosphors. In the present work, the vacancies at the host sites (V O , V X , V M , and V P ), anti-site defects (X O and O X ), and Ce 3+ -related defect complexes (Ce Sr –Na Sr , Ce Sr –Si P , and Ce Sr –O Cl ) are taken into consideration for the inquiry of the origin of the self-activated luminescence in the undoped MPOX and the assignment of the excitation bands of SPOC: Ce 3+ phosphors.…”

“…As an essential and helpful complement to experimental approaches, first-principles calculations can provide insight into the luminescent mechanisms of undoped and lanthanide-doped phosphors in light of the microscopic structure features of materials. − The wave function-based embedded-cluster ab initio calculations and their combination with the experiment have been performed in order to study the site occupations, charge-compensation mechanisms, and luminescent properties of the lanthanide ions in phosphors. − Multireference configuration–interaction calculations on the 4f 7 → 4f 6 5d 1 transitions of Eu 2+ ions (at both Sr(1) and Sr(2) sites) in the SrAl 2 O 4 and the comparison with the experimental excitation spectra reveal that the green luminescence is ascribed to the Eu 2+ ions at Sr(2) sites . Moreover, energetic stabilities, the locations of impurity states in the energy bands, and thermodynamic and optical transition energy levels of native defects and extrinsic dopants in phosphors are obtained from density functional theory (DFT) calculations, illuminating the experimental phenomena. − For example, Qu et al calculated the locations of defect levels due to the dopants (Eu, Ti, and Mg) and anion vacancies in Y 2 O 2 S, offering a comprehensive mechanism for the persistent luminescence with the eye-sensitive red color.…”

Multi-responsive deep-ultraviolet emission in praseodymium-doped phosphors for microbial sterilization

“…1a, during the high-temperature treatment. Energy traps can be formed from these defects for storing and releasing excitation energies, further generating PersL and PSL [30,31].…”

Non‐Rare‐Earth UVC Persistent Phosphors Enabled by Bismuth Doping

“…[24][25][26] To date, only a handful of UVC LPPs have been successfully developed, and all of them involve the use of rare-earth (RE) ion, Pr 3+ , as the UVC emitter. [25,[27][28][29] Given that REs are expensive due to the limited abundance in the earth and great imbalance between supply and demand, it is imperative to explore and develop non-REenabled UVC LPPs, which may not only enrich the bank of LPPs, but also offer new opportunities for rationally designing non-RE-activated phosphors.The ingredients for designing LPPs involve the choice of suitable emitters, hosts, and traps for either electrons or holes. The emission wavelength of LPPs is governed by the emitter [30] and the afterglow duration and intensity depend on the species and concentrations of traps with suitable depths; [31] in most cases structural defects can be employed as charge carrier traps.…”

“…[24][25][26] To date, only a handful of UVC LPPs have been successfully developed, and all of them involve the use of rare-earth (RE) ion, Pr 3+ , as the UVC emitter. [25,[27][28][29] Given that REs are expensive due to the limited abundance in the earth and great imbalance between supply and demand, it is imperative to explore and develop non-REenabled UVC LPPs, which may not only enrich the bank of LPPs, but also offer new opportunities for rationally designing non-RE-activated phosphors.…”