Rigid Nanoconfinement-Mediated Structural Robustness and Optical Stability in 3D and Quasi-2D Perovskite Nanowires under High Pressure

Metal halide perovskites are promising for optoelectronics but suffer from structural instability under high pressure. Herein, we demonstrate that rigid nanoconfinement within anodic aluminum oxide (AAO) templates effectively mitigates this issue. CsPbBr3 and quasi-2D PEA2FAn–1PbnBr3n+1 nanowires were synthesized within AAO pores and studied under high pressure. The nanoconfinement dramatically elevates the critical pressures for CsPbBr3 by 85–178% for isostructural transition (83–205% for structural phase transition) and delays the compression-mode transition in the quasi-2D system by ∼137%. This pressure hysteresis effect shows a positive correlation with decreasing pore diameter. Density functional theory calculations attribute this stabilization to a confinement-induced mechanical hardening and, crucially, the effective suppression of pressure-driven [PbBr6]4– octahedral rotations in CsPbBr3. This work establishes a general nanoconfinement strategy to enhance the extreme-condition durability of perovskite materials for demanding photonic applications.