Influence of Isomerism on Radioluminescence of Purely Organic Phosphorescence Scintillators

Abstract

There are few reports about purely organic phosphorescence scintillators, and the relationship between molecular structures and radioluminescence in organic scintillators is still unclear. Here, we presented isomerism strategy to study the effect of molecular structures on radioluminescence. The isomers can achieve phosphorescence efficiency of up to 22.8 % by ultraviolet irradiation. Under X-ray irradiation, both m-BA and p-BA show excellent radioluminescence, while o-BA has almost no radioluminescence. Through experimental and theoretical investigation, we found that radioluminescence was not only affected by non-radiation in emissive process, but also highly depended on the material conductivity caused by the different molecular packing. This study not only allows us to clearly understand the relationship between the molecular structures and radioluminescence, but also provides a guidance to rationally design new organic scintillators.Scintillators are a type of luminescence materials that can convert high energy photons or particles to visible photons, [1] which receive extensive attention in various fields, such as medical imaging [2] and irradiation detecting. [3] To date, scintillators are mainly divided into two categories, inorganic and organic scintillators. Compared with inorganic scintilla-

Ultralong Organic Phosphorescence: From Material Design to Applications

“…Experimental and calculated results demonstrated that the radioluminescence mechanism in the purely organic scintillators might be similar to the energy transfer process of electroluminescence (EL), including three steps: (1) absorption and conversion of X-ray to generate electrons and holes; (2) carrier transport process; (3) carrier recombination to produce 25% singlet excitons and 75% triplet excitons to generate luminescence. In a further study, we found the X-ray excited phosphorescence was also affected by the material conductivity caused by different molecular packing in three bromobenzoic acid isomer crystals ( 74 – 76 ) . After comprehensive analysis of PL, RL, and electrical conductivity of 74 and 76 scintillators, we concluded that good electrical conductivity is beneficial to radioluminescence by improving carrier transport and recombination.…”

“…In a further study, we found the X-ray excited phosphorescence was also affected by the material conductivity caused by different molecular packing in three bromobenzoic acid isomer crystals (74−76). 52 After comprehensive analysis of PL, RL, and electrical conductivity of 74 and 76 scintillators, we concluded that good electrical conductivity is beneficial to radioluminescence by improving carrier transport and recombination. These studies not only provide basic design principles for organic scintillators but also offer an opportunity for the development of flexible X-ray detectors for nondestructive radiographic testing, medical imaging, and others.…”

Halogen Bonding: A New Platform for Achieving Multi‐Stimuli‐Responsive Persistent Phosphorescence

“…Considering the complementary emission (host)‐absorption (guest) properties, an energy transfer may occur between the host and guest molecules (Figure S38) [25a, b] . After X‐ray irradiation, electrons and holes are generated in the host matrix, mainly through the photoelectric effect [17b] . These electrons and holes then recombine to generate massive singlet and triplet excitons with a ratio of 1 : 3.…”

Organic phosphorescent nanoscintillator for low-dose X-ray-induced photodynamic therapy

“…In view of the long-lived triplet excitons in purely organic luminogens 18 – 34 , phosphorescent materials can be made useful after improving their X-ray absorption. Modulation of halogen atoms with large atomic number Z (e.g., bromine and iodine) can improve the X-ray absorption ability 35 – 38 , because the attenuation coefficient ( μ ) is proportional to the fourth power of the atomic number ( μ ). Meanwhile, heavy halogen, oxygen, and nitrogen atoms benefit intersystem crossing (ISC) to populate the triplet excitons 39 .…”