With the surge in perovskite research, practical features for future applications are desired to be secured, but the reliability of the materials and the use of hazardous Pb are longstanding problems. Here, an air‐stable Cs2SnI6 (CSI) is prepared via diluted hydriodic acid solvent‐based precursor optimization during scalable hydrothermal growth. Materials characterization is performed using various elemental peak analyses and crystallographic identification. The resulting CSI exhibits long‐term operating stability over 6 months, i) at elevated temperatures, ii) in ambient air, and iii) under light illumination from UV to near‐infrared. More importantly, to demonstrate an intriguing class of applications up to system level, physically detachable CSI photodetector arrays (PD‐arrays), integrated with micro‐light‐emitting‐diodes (μ‐LEDs) arrays, are successfully fabricated. In addition, 3 × 3 flexible CSI PDs are fully operational, even in air, and their spatial uniformity in pixels is quantitatively evaluated. The charge‐transport mechanisms of the CSI PDs under light and elevated temperature are assessed via temperature‐dependent characterization from 148 to 373 K, implying the involvement of 3D variable‐range hopping. Multicycle evaluation of the CSI PD‐arrays confirms their operational stability in AC and DC modes, demonstrating this platform's potential benefit for wireless optical interconnection in advanced Si technology.
This study demonstrates the efficacy of an emerging p-type copper iodide (CuI) semiconductor in a flexible, low-voltage resistive random-access memory (RRAM), which can be readily integrated with metal-oxide n-type counterparts for complementary circuit systems. Herein, CuI RRAM devices are implemented via a room-temperature solid iodination process, exhibiting a consistent On/Off ratio (≈10 4 ), excellent endurance of more than ≈10 3 cycles, together with a long retention period (> 5 × 10 4 s). Furthermore, a scheme of light-mediated multi-level data storage is demonstrated using blue light illumination (λ = 455 nm), to exploit possible photonic memristive functionality through notable photo-response of CuI. In addition, the current conduction and resistive switching behaviors are systematically studied via low-temperature measurements from 203 to 343 K, validating thermal stability and the governing key switching mechanism in CuI RRAM devices. The longstanding problem with CuI device longevity is effectively addressed via PMMA encapsulation, resulting in a 15-fold improvement in the lifespan of devices even in air, as compared with non-passivated devices. These findings suggest that flexible optoelectronic systems, combined with reliable, ultra-low power CuI RRAM devices with photo memristive functionality, can leverage the enhancement of multifunctional selectors required in process-in-memories and the synaptic elements of neuromorphic applications.
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