Through-Space Charge-Transfer Organogold(III) Complexes Enable High-Performance X-ray Scintillation and Imaging

Abstract

Organic scintillators have recently attracted growing attention for X-ray detection in industrial and medical applications. However, these materials still face critical obstacles of low attenuation efficiency and/or inefficient triplet exciton utilization. Here we developed a new category of organogold(III) complexes, Tp-Au-1 and Tp-Au-2, through adopting a through-space interaction motif to realize high X-ray attenuation efficiency and efficient harvesting of triplet excitons for emission. Thanks to the efficient through-space charge transfer process, this panel of complexes achieved higher photoluminescence quantum yield and shorter radiative lifetimes compared with the through-bond reference complexes. Inspiringly, these organogold(III) complexes exhibited polarity-dependent emission origins: thermally activated delayed fluorescence and/or phosphorescence. Under X-ray irradiation, Tp-Au-2 manifested intense radioluminescence together with a record-high scintillation light yield of 77,600 photons MeV^-1 for organic scintillators. The resulting scintillator screens demonstrated high-quality X-ray imaging with >16.0 line pairs mm^-1 spatial resolution, outstripping most organic and inorganic scintillators. This finding provides a feasible strategy for the design of superior organic X-ray scintillators.

Keywords: X-ray imaging; organogold(III) complex; scintillators; thermally activated delayed fluorescence (TADF); through-space charge transfer (TSCT).