Pressure-Induced Suppression of Jahn–Teller Distortion and Optical-Optoelectronic Evolution in Distorted Perovskite TeCuO3

Perovskite oxides (ABO₃) exhibit structural flexibility and diverse properties, yet studies of highly distorted variants under high pressure (HP) remain scarce. Here, we synthesized the distorted perovskite TeCuO₃, which is characterized by octahedral tilting, Jahn–Teller (JT) distortion, and G-type antiferromagnetism (AFM). Using in situ HP synchrotron single-crystal X-ray diffraction (SCXRD), Raman and absorption spectroscopy, photocurrent measurements, and first-principles calculations, we examined its structural, optical, and optoelectronic properties up to 45.9 GPa. TeCuO₃ maintains its Pnma symmetry but undergoes a magnetic transition from G- to A-type AFM at ∼1.7 GPa. Pressure suppresses CuO₆ tilting and JT distortion due to the stereochemical activity of Te⁴⁺ lone pairs, with equatorial JT distortion vanishing at 25 GPa. These changes drive a reversible piezochromic shift from light-colored to opaque black, attributed to a red-shifted p–d transition merging with d–d absorption. Notably, the optoelectronic response intensifies by 50% at 47 GPa. These findings provide insight into the HP evolution of distorted perovskites and highlight the potential of TeCuO₃ for pressure-tunable optoelectronic applications.