Room-temperature spin organic light-emitting diodes based on two-dimensional Dion–Jacobson perovskites

Spin-optoelectronics plays a key role in the development of next-generation electronics, with potential applications ranging from optical communications to quantum computing. Spin organic light-emitting diodes have usually been realized via spin injection from ferromagnetic electrodes. In this work, spin injection was realized by using solution-processed chiral perovskites as spin filters under the emitting layer. To realize spin organic light-emitting diodes, Dion–Jacobson (DJ) phase two-dimensional chiral perovskites based on 4-(aminomethyl)piperidinium (4-AMP) with different stoichiometric ratios 〈n〉 were first investigated. Based on the absorbance and photoluminescence spectra, and X-ray diffraction patterns, it was found that the DJ perovskite film with 〈n〉 = 1 was (4-AMP)PbBr₄, and DJ perovskite films with 〈n〉 = 2, 3 was a mixture of (4-AMP)(MA)_n−1Pb_nBr_3n+1 with various n values. All DJ perovskite films exhibited the vertically preferred orientation of the perovskite slab. Derivative circular dichroism features centered at the absorption peak (395 nm) could be observed from these DJ perovskite films, indicating the splitting of the energy levels. The derivative features in magnetic circular dichroism spectra were centered at the exciton absorption peaks and band edges. The g_abs values and the Zeeman splitting energy values were derived. Magnetic circularly polarized luminescence spectra were also observed at room temperature and attributed to the spin-preserved energy funneling. Spin organic light-emitting diodes were realized by using these chiral perovskites as the spin filter. Circularly polarized electroluminescence (CPEL) was observed at room temperature without an external magnetic field. Besides, perovskite light-emitting diodes were also investigated by using these chiral perovskites as the emissive layers. It was observed that air exposure had a strong influence on the film morphology, perovskite slab orientation, and device performance.