In particular, PCs based on stimuliadaptive self-assembled colloids, [13][14][15] layer-by-layer, [16,17] and block copolymers (BCPs) [1,4,5,6,[8][9][10][11][12] are suitable for reflectivemode electric-switching (E-switching) SC displays because of their cost-effectiveness, facile development of full-visible color, and mechanical flexibility. The most common E-switching PC devices reported are fabricated into liquid cell-type systems in which various E-field-responsive PCs are embedded in various liquid media (Table S1, Supporting Information). [18][19][20][21][22][23][24][25] The liquid solvent medium employed in E-switching devices maintains a stable dispersion of ordered colloids in colloidal PCs [18][19][20][21] and swells targeted domains in BCP PCs with an E-field. [22][23][24][25] Despite the fast SC switching arising from the rapid kinetics of the solvent, most liquid-cell BCP SC display applications are limited because of their lack of mechanical flexibility and complex fabrication processes required to prevent solvent leakage.Solid-state E-switching PC devices have been developed to resolve this issue (Table S1, Supporting Information). [26][27][28][29] Recently, solid-state E-switching colloidal PC devices were established by encapsulating self-assembled colloidal particles in a polymer matrix. [26][27][28] Dielectric elastomer actuation was implemented in this system, where the external electrical stimulus induces Maxwell stress across the dielectric medium with the PCs. Field-dependent alteration in the periodicities of the colloidal PCs gives rise to E-switching SCs in the full visible range. However, it is unfortunate that such actuation of a few hundred micrometers-thick PC often requires a high E-field of ≈22.5 V µm −1 , [26] corresponding to an operation voltage ranging from 4 to 9 kV. [26][27][28] Only a few Soft-solid photonic crystals (PCs) based on periodically ordered block copolymer (BCP) nanostructures demonstrate stimuli-adaptive structural colors (SCs) and desirable mechanical properties suitable for reflective-mode electricswitching (E-switching) displays. However, the low electrochemical stability and humidity-dependent E-switching performance of hygroscopic ionic salts, often employed for E-field-adaptive structural alteration, limit their applications. In this study, a low-powered capacitive E-switching BCP SC display with an organohydrogel (OH) humidity controller is proposed, where a bilayer of a BCP and a polymer blend with hygroscopic E-field-adaptive ionic salts is sandwiched between Au electrodes. The display reliably exhibits reversible full-color E-switching (100 on/off cycles) at operating voltages of +2.5 to −2 V within the ionic salts' electrochemical window at ≈50% humidity. A patchable and reusable OH serves as a water reservoir (with optimized geometries and dimensions) to improve the display's humidity tolerance, providing a target humidity (≈50%). The proposed display performs at ambient humidity lower than 60% for over 10 days because of the long water retention an...

Block Copolymer Structural Color Display Humidity‐tolerant and electrochemically stable block copolymer structural color display is developed, based on one‐dimensional block copolymer photonic crystal and an organohydrogel acting as humidity controller, making it suitable for emerging reflective‐mode interactive displays. More information can be found in article number 2200385 by Cheolmin Park and co‐workers.