Chirality–Racemization Strategy Toward Copper (I) Iodide Hybrid Single‐Crystalline Scintillators for X‐Ray Detection and Imaging Applications

Abstract Organic–inorganic hybrid copper(I)‐based halides have attracted great interest in the field of optoelectronics due to their low cost, non‐toxicity, large Stokes shift, and high photoluminescence quantum yields (PLQYs). Here, bulk zero‐dimensional (0D) organic‐inorganic hybrid copper(I)‐based (R,S‐2‐mpip)₂Cu₂I₆ (mpip = methylpiperazinium, C₅H₁₄N₂²⁺) single crystals have been grown with equal stoichiometric ratios of R‐ and S‐2‐mpip ligands by chirality–racemization strategy for the first time. Interestingly, (R,S‐2‐mpip)₂Cu₂I₆ single crystals exhibit strong blue–green photoluminescence (PL) located at 520 nm with large Stokes shift of about 230 nm and high PLQY of about 65.96%, which originates from self‐trapped excitons (STEs). More importantly, (R,S‐2‐mpip)₂Cu₂I₆ single crystals also exhibit the strong radioluminescence (RL) at 520 nm, the fast X‐ray scintillation response with a light yield of about 47 000 photon MeV⁻¹ and low detection limit of 6.48 nGy_airs⁻¹ when exposed to X‐ray irradiation condition, which is superior to that of other copper(I) iodide‐based hybrids. Based on the excellent characteristics, X‐ray imaging systems based on (R,S‐2‐mpip)₂Cu₂I₆ single crystals exhibit the clear images of “QFNU” logo and crystal symbol pattern. This work not only deepens the understandings of material design and fundamental properties of these racemate systems, but also provides guidance for the further applications in the multi‐functional optoelectronics.