Host molecule enhanced aggregation induced emission of chiral silver nanoclusters for achieving highly efficient circularly polarized electroluminescence
Ye Tian, Shuhe Hu, Xiaoyu Zhang, Hang Gao, Yanwei Xiao, Yinghui Wang, Dong Yao, Hao Zhang
Abstract
Chiral metal nanoclusters (MNCs) are competitive candidates for fabricating circularly polarized light-emitting diodes (CPLEDs), but the device performance is greatly limited by the poor emission of MNCs in solid thin films. Herein, host molecule enhanced aggregation induced emission (AIE) of MNCs is demonstrated for fabricating highly efficient CPLEDs. Namely, on the basis of the AIE effect of atomically precise enantiomeric (R/S)-4-phenylthiazolidine-2-thione capped silver (R/S-Ag6(PTLT)6) NCs in solid thin films, 1,3-bis(carbazol-9-yl) benzene (mCP) is introduced as a host molecule to control the orientation and packing arrangements of R/S-Ag6(PTLT)6 NCs through π—π interactions with the R/S-Ag6(PTLT)6 NCs and further enhance the AIE. The as-fabricated Ag6(PTLT)6 NC/mCP hybrid solid thin film shows a high photoluminescence quantum yield of 71.0% close to that of Ag6(PTLT)6 NC single crystal. As the hybrid films are employed as the active emission layers of CPLEDs, mCP also suppresses the triplet-triplet annihilation and balances the charge transport. Thus, the CPLEDs exhibit a maximum brightness of 3,906 cd/m2, peak external quantum efficiency of 10.0%, and electroluminescence dissymmetry factors of −5.3 × 10−3 and 4.7 × 10−3.