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. PEA4 Cu4 I4 is an efficient orange-red broad emission with a highest PLQY of 73.6%. All three materials, namely, those of ((R)-(+)-α-PEA)4 Cu4 I4 , ((S)-(-)-α-PEA)4 Cu4 I4 , and (β-PEA)4 Cu4 I4 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.