Large‐Scale Room‐Temperature Synthesis of the First Sb3+‐Doped Organic Ge(IV)‐Based Metal Halides with Efficient Yellow Emission for Solid‐State Lighting and Latent Fingerprint Detection

Organic–inorganic hybrid Ge(II)‐based metal halides have garnered significant interest due to their intriguing photophysical properties and environmentally friendly characteristics. However, challenges such as poor stability, low emission intensity, and a complex synthesis process have hindered their widespread application. In addressing these issues, a breakthrough in the large‐scale production of Sb 3+ ‐doped Ge(IV)‐based metal halide (C 13 H 14 N 3 ) 2 GeCl 6 phosphors at room temperature through a straightforward solution method is presented. The synthesized compound exhibits a remarkable bright broad yellow emission band at 590 nm, boasting a photoluminescence quantum efficiency of 99.53 ± 0.06% the highest among Ge(IV)‐based metal halides. Notably, the introduction of Sb 3+ induces the formation of Jahn–Teller‐like self‐trapped excitons in [SbCl 6 ] 3− species, attributable to lattice distortion and strong electron–phonon coupling. Consequently, Sb 3+ ‐doped (C 13 H 14 N 3 ) 2 GeCl 6 demonstrates a large Stokes shift (221 nm) and a prolonged decay lifetime (3.06 μs). Furthermore, the Sb 3+ ‐doped compound exhibits commendable chemical‐ and photostability, prompting exploration in applications such as white light‐emitting diodes and latent fingerprint detection. This work not only provides a practical approach for designing economically viable, environmentally friendly, and highly efficient emission phosphors but also paves the way for novel directions in their expanded application.