Dual‐Encrypted Ultraviolet Optical Communication Driven by Opto‐Piezoelectric Coupling in Two‐Dimensional Flexible Ferroelectric Single‐Crystalline Thin‐Films

The rapid development of flexible wearable electronics has triggered an urgent demand for high‐security and miniaturized encrypted optical communication systems. However, conventional optical encryption strategies predominantly rely on dual‐wavelength excitation, tunable light sources, or software‐based algorithms, leading to bulky configurations and vulnerable hardware‐level security. Herein, we report a dual‐encrypted ultraviolet optical communication system based on BA 2 EA 2 Pb 3 Br 10 ( 1 , where BA is n‐butylamine and EA is ethylamine) ferroelectric single‐crystalline thin‐films (SCFs). The 1 ferroelectric SCFs show a photoresponsivity that reaches 230% of the original level under +1.13% tensile strain. Notably, we innovatively define the strain‐ratio key (ε 1 /ε 2 , ε 2 /ε 3 , ε 3 /ε 4 ) induced by distinct bending states as the intrinsic unclonable hardware secret key, and construct a 4‐bit combined coding scheme based on four distinguishable photocurrent levels modulated by these strain ratios to realize secure transmission of the message “FJIRSM.” This strain ratio‐based system avoids complex optical modulation, ensuring ultrahigh security, and expands the application of two‐dimensional ferroelectrics in advanced encrypted optoelectronics.