Pressure‐Induced Dual Self‐Trapped Exciton Emission and Circular Dichroism Inversion in 1D Chiral Organic–Inorganic Lead Halides

Simultaneous precise control over luminescence and chiroptical activity in a single crystalline platform is a long‐standing goal for chiral optoelectronics. 1D chiral organic–inorganic lead halides (OILHs) are ideal candidates due to their diverse self‐trapped excitons (STEs) emissions and circular dichroism (CD) responses. However, the microscopic origins of STE diversity and CD inversion remain controversial, limiting targeted optimization. This work employs high pressure to trigger highly efficient dual STE emission with CD inversion in 1D chiral OILH R ‐C 5 H 14 N 2 PbCl 4 ·H 2 O, which is based on significantly strengthened octahedral coupling. Excited‐state configuration coordinate calculations and transient spectroscopy reveal that this strengthened octahedral coupling intensifies octahedral distortion and transient structural deformation, which facilitate the formation of dual polaron‐pair STEs while deepening the STE trapping depth and elevating the quenching barrier. This confirms that polaron‐pair STEs can be converted from nonradiative into efficient radiative recombination centers, resolving the controversy over polaron‐pair STEs’ luminescence efficiency. Furthermore, CD calculations based on the same chiral configuration demonstrate that enhanced octahedral coupling and distortion alter the predominance of two groups of transitions with opposite rotational strengths, inducing the CD inversion even without changing the intrinsic chirality. These findings provide a blueprint for designing OILHs with efficient luminescence and programmable chiroptical properties.