Multigated Photochromic Materials: Mechanism, Progress, and Application

Photoresponsive materials offer unique opportunities for advanced technologies by enabling their precise, noncontact remote control and converting light energy into well-defined changes in structure and function. Among them, multigated photochromic systems have emerged as a transformative frontier, overcoming constraints of conventional single-stimulus systems. Here, "gated" refers to the deliberate use of an additional external input (e.g., pH, voltage, mechanical force, or temperature) to regulate or modulate the photoisomerization process. Such multi-input control enables sophisticated, programmable behaviors, including Boolean logic operations, environmental adaptation, and high-security information encryption, thereby marked expanding their application potential. In this review, we present a comprehensive and systematic analysis of multigated photochromic materials. We first introduce a unified design strategy and classification framework based on gating mechanisms. The core sections critically evaluate recent advances in proton-, electro-, mechano-, thermal-, and wavelength-gated systems, with particular emphasis on the underlying principles that connect molecular design to tailored performance. Furthermore, we discuss emerging and unconventional gating modes, including ion-, liquid-, gas-, and intensity-gated photochromism. Finally, we present a comparative analysis of all gating modalities, identify persistent conceptual and practical challenges, and outline future directions toward intelligent, adaptive material platforms. This review aims to establish a foundational framework that guides the rational design of next-generation multigated photochromic materials for applications in sensing, anticounterfeiting, information technology, and adaptive devices.