Zero‐Dimensional Organic–Inorganic Hybrid Copper‐Based Halides with Highly Efficient Orange–Red Emission

Lead‐free metal halides are promising luminescent materials with low non‐toxicity, tunable emission, and high luminescence quantum yield (PLQY). The development of red light‐emitting materials with high PLQY to meet the color coordinate requirements for light‐emitting diode (LED) lighting and wide color gamut displays remains a major scientific challenge. Herein, novel lead‐free copper‐based halide materials are reported. PEA 4 Cu 4 I 4 is an efficient orange–red broad emission with a highest PLQY of 73.6%. All three materials, namely, those of ((R)‐(+)‐α‐PEA) 4 Cu 4 I 4 , ((S)‐(–)‐α‐PEA) 4 Cu 4 I 4 , and (β‐PEA) 4 Cu 4 I 4 with zero‐dimensional structures have large exciton binding energies and Huang–Rhys factors, thus causing efficient self‐trapped exciton emissions. A prototypical orange–red LED device is fabricated successfully that demonstrates the potential of copper‐based halide materials in lighting and display applications.