Stable Full‐Color and Single‐Phase White Emission in a Family of Isomeric Organic Cu(I) Iodides

ABSTRACT Organic Cu(I) halides feature highly designable structures, systematic tunability, and efficient emission; however, simultaneously achieving full‐color tunable emission and single‐phase white emission with thermal‐ and chemical‐stimulated optical responses in organic isomeric Cu(I) halides polymorphs have never been reported. Herein, we synthesized a family of zero‐dimensional organic isomeric Cu(I) iodides of α‐/β‐/γ‐/δ‐/ε‐(ITPP) 2 Cu 2 I 4 , all of which have the same molecular formula and crystallize in monoclinic space group P 2 1 / n . However, due to the different arrangement orientation of [Cu 2 I 4 ] 2− clusters and the surrounding molecular environment, α‐/β‐/γ‐/δ‐/ε‐(ITPP) 2 Cu 2 I 4 exhibits blue, green, yellow, red, and white emission, with an optimal luminous efficiency of 92.4%. Interestingly, α‐/β‐/γ‐/δ‐/ε‐(ITPP) 2 Cu 2 I 4 shows tunable dual self‐trapped excitons emission under different temperatures, making them suitable for optical thermometry with an ultrahigh relative thermal sensitivity of 13.17% · K −1 . Moreover, external chemical stimuli can induce luminescent transformation between different hybrid Cu(I) iodides, which enables us to demonstrate their application in multiple anti‐counterfeiting. Parallelly, hybrid Cu(I) iodides also exhibit efficient x‐ray scintillation with a high light yield of 63500 ± 1200 photons/MeV, and a customizable large‐area flexible paper‐based film has been prepared in situ using an “ancient fabric dyeing process”, demonstrating its application in x‐ray imaging with an ultrahigh spatial resolution of 20.8 lp/mm.