CsPbI₃ Perovskite Quantum Dot-Based WORM Memory Device with Intrinsic Ternary States

Area of Science:

• Materials Science
• Nanotechnology
• Solid-State Electronics

Background:

• Mobile ionic halide vacancies in perovskites typically degrade device performance and stability.
• Perovskite quantum dots (PQDs) offer unique optoelectronic properties but face challenges in memory applications.

Purpose of the Study:

• To leverage the intrinsic migration of halide vacancies in CsPbI3 PQDs for a novel WORM memory device.
• To demonstrate and understand the mechanism behind intrinsic ternary states and multilevel properties in PQD-based memory.

Main Methods:

• Fabrication of a CsPbI3 PQD-based sandwich structure WORM memory device.
• Electrochemical impedance spectroscopy (EIS) to analyze resistive switching mechanisms.
• In situ conductive atomic force microscopy (in situ c-AFM) to investigate defect migration and conductive filament formation.

Main Results:

• Achieved a WORM memory device with intrinsic ternary states and a high ON/OFF ratio (10^3:10^2:1).
• Demonstrated a long retention time of 10^4 s.
• Confirmed resistive switching is driven by electric-field-induced migration of iodine vacancies (V_Is) forming conductive filaments (CFs).
• Revealed multilevel properties stem from distinct activation energies for V_I migration at grain boundaries versus grain interiors, creating dual CF growth pathways.

Conclusions:

• The controlled migration of ionic defects, specifically iodine vacancies, can be harnessed to create high-performance WORM memory devices.
• CsPbI3 PQDs offer a promising platform for simple yet effective multilevel WORM memory with excellent stability and retention.
• This work opens new avenues for defect engineering in perovskite materials for advanced electronic applications.