A Programmable Semiconductor Containing Active Molecular Photoswitches Located in the Crystal's Volume Phase

Abstract Exponential increases in information storage and computing demand associated with more energy consumption push the limits of micro‐ and nanoelectronics, necessitating radically new technologies. All‐optical synaptic and neuromorphic devices promise breakthroughs with their superior processing power and energy efficiency, but they require adaptive semiconductors. Unlike traditional materials (silicon, III/V, II/VI compounds), these semiconductors can reversibly alter their optical and optoelectronic properties in response to stimuli, supporting computing functions while holding memory values in either continuous or binary states. The study presents layered hybrid perovskites composed of organic layers with an active Coumarin species, which can be photochemically switched up to 70% and back. The [2+2] cycloaddition causes local distortions in the lead halogenide layers, modifying the band structure, and transforming the bandgap and photoluminescence based on the switching degree. The reaction facilitates high spatial precision in pattern creation, enabling the design of complex semiconductor and optical features within homogeneous films.