Persistent Photoluminescence Superlinearity Beyond Static Recombination Physics in Metal Halide Perovskites

ABSTRACT Persistent intermediate power‐law exponent (β) values in metal halide perovskites commonly occur across excitation regimes in which assignment to a single carrier‐population recombination limit becomes ambiguous. Their strong dependence on excitation conditions further indicates that excitation‐dependent photoluminescence cannot always be interpreted uniquely through a static Shockley‐Read‐Hall (SRH)‐bimolecular‐Auger recombination picture. Here, power‐dependent and time‐resolved photoluminescence measurements on methylammonium lead iodide (MAPbI 3 , MA = CH 3 ​NH 3 ) thin films reveal correlated evolution of excitation scaling, delayed emission, and illumination‐history response under conditions that systematically modify vibrational dissipation and carrier‐relaxation pathways. These behaviors are described using a dual‐channel framework in which transient vibrational energy retention contributes to delayed radiative response. The results support an interpretation of PL superlinearity as an emergent, condition‐dependent response associated with coupled carrier‐lattice relaxation dynamics, rather than a simple transition between fixed recombination‐order limits. More broadly, these results show that β and photoluminescence quantum yield (PLQY) should not be treated as fixed intrinsic material constants, but as excitation‐conditioned observables shaped by the evolving relaxation environment, highlighting limitations in interpreting PL scaling laws as direct indicators of recombination pathways in soft semiconductors.