Pressure‐Induced Ultra‐Red‐Shift From Visible to Near‐Infrared and Enhanced Emission in Inorganic Halide Perovskite CsGeBr 3

ABSTRACT Extending the spectral response of metal halide perovskites into the infrared (IR) region remains a long‐standing goal for advanced optoelectronic applications. In this work, we realize an unprecedented ultra‐red‐shift absorption and emission, spanning from the visible region to the IR window, in the environmentally friendly Ge‐based halide perovskite CsGeBr 3 through pressure engineering. Remarkably, upon compression, the initially weak‐emissive CsGeBr 3 evolves into a bright photoluminescent (PL) material, displaying two distinct emission peaks. An enhancement in photoluminescence quantum yield (PLQY) is achieved, accompanied by red shifts of up to 469 and 413 nm for the two peaks, respectively. Pressure‐induced symmetry rise restrains Ge 2+ lone‐pair activity, reduces octahedral distortion and strengthens Ge─Br orbital coupling, narrowing the band gap. The band structure calculation and electron localization function analyses confirm such pressure‐regulated band‐gap evolution and lone‐pair effects. Further compression drives Ge atoms to the octahedral centers, inducing a rhombohedral‐to‐cubic transition with complete PL quenching. Our findings provide key insights into extending the spectral response of halide perovskites into the IR region and offer new design principles for optoelectronic materials via lattice‐modulation engineering.