Deuterated perovskite for room temperature spin device.

Organic-inorganic hybrid perovskites (OIHPs) offer a promising alternative, combining strong spin-orbit coupling, high carrier mobility, and tunable optoelectronic properties. However, their potential for spintronic applications has been constrained by rapid spin relaxation, often attributed solely to the inorganic sublattice. Here, we demonstrate room-temperature spin transport in hybrid perovskites enabled by isotope engineering. Substituting hydrogen with deuterium in methylammonium lead iodide effectively suppresses hyperfine interactions (HFI), leading to a 2.6-fold increase in spin lifetime. As a result, CD₃ND₃PbI₃ exhibits a magnetocurrent (MC) ratio of 17.5% at room temperature, whereas conventional CH₃NH₃PbI₃ spin-valve devices show negligible MC response. A spin photovoltaic effect is also observed under ambient conditions, revealing a coupling between optical excitation and spin-polarized transport, and pointing toward new opportunities for light-addressable spintronic functionality. These findings not only revise the fundamental understanding of spin relaxation in hybrid materials, but also establish isotope engineering as a powerful strategy to access room-temperature spin functionality.