Recently, the research team led by Researcher Wu Kaifeng and Associate Researcher Cheng Pengfei from the Photoelectronic Materials Dynamics Group (Group 1121) at the Chemical Kinetics Laboratory of the Dalian Institute of Chemical Physics, Chinese Academy of Sciences, has made significant progress in the study of metal halide luminescence dynamics. Their work reveals the regulatory effect of doping on the circularly polarized luminescence behavior of chiral metal halides, achieving highly efficient circularly polarized cyan emission and effective second harmonic generation in organic-inorganic hybrid silver-based halides.
Circularly polarized light carries rich optical information and holds significant application potential in imaging, sensing, and photonics. In recent years, chiral metal halides exhibiting circularly polarized emission have garnered considerable attention due to their low cost and solution-processable nature. However, the chirality in these materials primarily originates from chiral organic cations introduced into their structures, whose limited variety severely restricts the tunability of material composition. Furthermore, the circularly polarized emission of currently reported chiral metal halides is predominantly concentrated in the green, orange, and red regions, while blue circularly polarized emission-crucial for high-performance lighting and optical communications-remains unattained.
In this work, the research team assembled zero-dimensional chiral silver halides by combining achiral methyl-triphenylphosphine cations with triangular silver-iodine inorganic units. Through copper ion doping, the team not only enhanced the material's luminescence efficiency but also imparted circularly polarized luminescence activity, thereby extending circularly polarized emission in metal halides to the blue region. Spectroscopic characterization revealed that copper doping not only effectively suppresses nonradiative recombination in the host matrix but also introduces new copper-associated luminescent centers. This approach achieves a fluorescence quantum yield approaching 100% and yields an emission asymmetry factor of 1.3 × 10⁻². Furthermore, the intrinsic non-centrosymmetric structure of this chiral system endows it with polarization-sensitive second harmonic response and exhibits significant second harmonic circular dichroism. This work proposes a chiral optical modulation strategy for metal halides that does not rely on chiral cations, offering a novel approach for designing metal halides with both circularly polarized luminescence activity and nonlinear optical response.
This work, titled "Bright Cyan Circularly Polarized Luminescence and Efficient Second Harmonic Generation in Zero-Dimensional Silver-Based Halides with Achiral Cations," was recently published in Angewandte Chemie International Edition. The co-first authors are Wang Sijia, a doctoral graduate from our institute, and Bai Tianxin, a postdoctoral researcher in Group 1121. This research was supported by the National Natural Science Foundation of China, the Chinese Academy of Sciences Category B Pioneer Special Project "Precise Detection of Chemical Reaction Transition States Using Extreme Ultraviolet Light Sources," the Central Universities Basic Research Fund, and the Institute's Innovation Fund.
