Substrate‐Controlled Photoluminescence Memory Behavior in a Perovskite–GeSbTe Photonic Platform

All‐optical neuromorphic computing promises ultrafast and energy‐efficient information processing compared to classical von Neumann architecture. To realize this bio‐inspired platform, its memory elements should combine volatility and nonvolatility within a single memory device. Here, we report a hybrid optical memory device that integrates volatile photophysical dynamics with nonvolatile phase‐change control. The platform consists of a luminescent CsPbBr 3 halide perovskite thin film deposited on a Ge 2 Sb 2 Te 5 substrate. In this device, reversible amorphous‐crystalline phase transitions provide a modulation of the CsPbBr 3 photoluminescence properties. Time‐resolved photoluminescence measurements reveal excitation‐history‐dependent dynamics governed by photodoping and trap filling in the perovskite layer, while the GST phase sets the nonvolatile emission intensity. Finally, we realize all‐optical classification of binary pulse sequences using a pixelated hybrid device. These results establish a materials platform for hybrid optical memory and open new pathways toward adaptive neuromorphic photonic systems.