Dominant Dark-Exciton Transport in 2D Metal–Halide Perovskites

Excitons in 2D hybrid metal–halide perovskites exhibit rich spin–orbit interactions and strong Coulomb correlations, making them a fertile ground for exploring excitonic transport physics. In this work, we reveal that dark excitons, rather than bright ones, govern photocurrent transport in 2D hybrid metal–halide perovskites. Low-temperature photocurrent spectroscopy shows a strong magnetic-field dependence, evidence that the dark-state population dominates charge transport. Our findings identify dark excitons as efficient carriers for exciton-mediated conductivity and point toward spin-optoelectronic applications exploiting dark-state transport in low-dimensional perovskites.