Optimizing Spin Polarization in Spin-LEDs Based on Chiral Perovskites via Material Engineering

Chiral hybrid perovskites are promising materials for spin-polarized light-emitting diodes (spin-LEDs), using the chirality-induced spin selectivity (CISS) effect to generate circularly polarized electroluminescence without a ferromagnetic electrode. However, the relation between material structure, spin dynamics, and device performance remains unclear. Here, we use magneto-electroluminescence (MEL) to probe spin-dependent processes in chiral perovskite spin-LEDs. We show that spin polarization can be enhanced through two strategies: tuning the content ratio of chiral components to strengthen spin filtering, and optimizing film morphology via thermal annealing to improve spin transfer efficiency. Devices with a higher fraction of the chiral 2D phase exhibit stronger CISS-mediated spin injection, while smoother, fine-grained films better preserve spin polarization during transfer to the emitting sites. Our findings clarify the material-spin-performance relationship in chiral perovskites and provide practical guidelines for developing efficient spin-optoelectronic devices.