A Threefold Symmetric NDI‐Nanohoop With a Large Stokes Shift: A Red‐Emitting Dye for Inorganic Electroluminescence

Nanohoops with radial π‐conjugation, such as cycloparaphenylenes (CPPs), exhibit intrinsically large Stokes shifts arising from excited‐state symmetry breaking. However, their integration into functional electroluminescent platforms has remained largely unexplored. Herein, we report the synthesis of a threefold symmetric naphthalenediimide (NDI)‐embedded CPP analogue ( [3]CDPNDI ) and its application in inorganic powder electroluminescence (iEL) devices. [ 3 ]CDPNDI was obtained in only four steps with 63% overall yield. The incorporation of electron‐accepting NDI units extends the emission into the red region (λ em = 630 nm, Φ F = 37%, in CHCl 3 ) with a large Stokes shift of 136 nm (4370 cm −1 ), which is advantageous for suppressing self‐absorption. AC field‐driven iEL devices achieved reddish‐purple emission consistent with one‐step color conversion of ZnS emission. Notably, the nanohoop emitter was integrated into the device via a simple solution‐coating process by incorporating 1 wt% [3]CDPNDI into the ZnS‐based phosphor paste, and EL emission remained observable after the devices were formed into origami‐ and kirigami‐type architectures. This work demonstrates the integration of a red‐emissive NDI‐embedded nanohoop into a solution‐processable ZnS‐based iEL platform and its compatibility with mechanically reconfigurable device architectures.