Chiral Copper(I) Iodide Cluster Hybrids Enabling Highly Efficient Circularly Polarized Electroluminescence

While the emergence of copper(I)-iodide cluster hybrid materials as potential substitutes for toxic lead halides in electroluminescence applications represents a major advancement, electroluminescence efficiency still needs improvement and in fact circularly polarized electroluminescence (CPEL) remains largely unexplored. In this work, the design of chiral phosphine ligands is dedicated to attaining strongly luminescent copper(I)-iodide cluster hybrid materials, thus achieving high-efficiency CPEL through a host-guest doping strategy. The chiral copper(I)-iodide cluster hybrids exhibit intense yellow emission peaked at 567 nm with notable circularly polarized luminescence (CPL). Doping films comprising 30% 1,3-bis(N-carbazolyl)benzene (mCP), 30% 2,6-bis(3-(9H-carbazol-9-yl)phenyl)pyridine (2,6-DCZPPY), and 40% chiral Cu2I2 cluster hybrids demonstrated excellent CPL with a quantum yield (PLQY) exceeding 80% and low surface roughness of 0.358 nm. Based on this, electrically driven light-emitting diodes (LEDs) with a CPEL dissymmetry factor (gEL) of 1.36x10-3 and a peak external quantum efficiency (EQE) of 20.5% are successfully developed. Notably, this work not only represents the first demonstration of CPEL in Cu(I) halide clusters but also provides one of the top device efficiencies for non-lead metal halide materials.