However, the low X-ray absorption cross-section and subsequently poor detection sensitivity of organic scintillators due to their limited effective atomic numbers have substantially impeded their applications. Introduction of halogen heavy atoms (Cl, Br, and I) into scintillators are effective methods to significantly increase their X-ray absorption cross-section, X-ray sensitivity, and imaging resolution . Nevertheless, traditional through-bond conjugated connections between halogen heavy atoms and emitters generally facilitate the (R)ISC process but enhance the nonradiative decay rate, which quenches their luminescence to result in low PLQYs (Fig. ). Consequently, the search for an appropriate molecular engineering approach to retain or enhance the RL properties with introducing heavy atoms is of great importance to generate new high-performance organic scintillators. Here, we proposed a novel concept for designing organic scintillators based on nonconjugated alkyl bromide, in which heavy atom-π interactions penetrate the space between scintillators and heavy atoms, promoting the spin-orbital coupling (SOC) between single and triplet states without increasing nonradiative decay (Fig. ). In this motif, emitters and heavy atoms are spatially separated, but meanwhile allowing external, rather than the internal heavy atom effect to occur. This concept has the following advantages. Firstly, the emitters and heavy atoms can interact with each other through spatial interactions to enhance the X-ray absorption cross-section. Secondly, the spatial separation of emitters and heavy atom units will promote SOC between singlet and triplet states, which can facilitate the (R)ISC process and increase the exciton utilization efficiency. Thirdly, the nonconjugated architecture avoids the strong nonradiative decay of singlet excitons resulted from the heavy atoms. Therefore, considerable PLQY can be expected. As a result, the optimal balance among large Stokes shift (> 100 nm), high PLQY (100%) and short decay time (3.74 ns) of organic scintillation materials can be achieved simultaneously by HLCT emitters with attaching through-space bromines. In this work, an X-ray scintillator named BTD-HeBr was designed and prepared. It exhibits a narrow RL spectrum with FWHM of 56 nm, high light yield of approximately 42,400 photons MeV -1 and a low detection limit of 84.6 nGy s -1 . More importantly, a high X-ray imaging resolution of > 40.0 line pairs per millimeter (lp mm -1 ) was achieved, which is the highest value for organic scintillators reported so far. This finding provides a powerful design approach and promising new alternative materials for fabricating organic X-ray imaging scintillators with outstanding sensitivity, low cost and high stability using through-space heavy atom-π interactions involving HLCT emitters.