High photoluminescence quantum yield modulation of zero-dimensional organic–inorganic Mn( <scp>ii</scp> ) metal halides by substituent modification

Organic-inorganic hybrid metal halides have emerged as promising luminescent materials owing to their structural tunability and exceptional photoluminescence modulation capabilities, showing great potential in optoelectronic applications. Herein, we report the successful design of a novel series of zero-dimensional (0D) Mn(II)-based organic-inorganic hybrid halides with enhanced photoluminescence quantum yields (PLQYs) through strategic organic cation engineering. Specifically, in this paper, the methyl group (-CH₃) at the fourth position of the benzene ring in the organic cation was replaced with hydrogen (-H) and cyano (-CN) groups. The average distance of Mn⋯Mn was successfully adjusted from 8.925 Å to 8.970 Å and 8.986 Å, and the PLQY was modulated from 35.74% to 59.04% and 81.38%. This work establishes a new paradigm for rationally designing high-performance luminescent materials through molecular-level structural engineering, providing valuable insights for developing advanced optoelectronic devices in sensing, information encryption, and radiation detection applications.