Modulating the optical and electrical properties of MAPbBr3 single crystals via voltage regulation engineering and application in memristors

Defect density is one of the most significant characteristics of perovskite single crystals (PSCs) that determines their optical and electrical properties, but few strategies are available to tune this property. Here, we demonstrate that voltage regulation is an efficient method to tune defect density, as well as the optical and electrical properties of PSCs. A three-step carrier transport model of MAPbBr3 PSCs is proposed to explore the defect regulation mechanism and carrier transport dynamics via an applied bias. Dynamic and steady-state photoluminescence measurements subsequently show that the surface defect density, average carrier lifetime, and photoluminescence intensity can be efficiently tuned by the applied bias. In particular, when the regulation voltage is 20 V (electrical poling intensity is 0.167 V μm−1), the surface defect density of MAPbBr3 PSCs is reduced by 24.27%, the carrier lifetime is prolonged by 32.04%, and the PL intensity is increased by 112.96%. Furthermore, a voltage-regulated MAPbBr3 PSC memristor device shows an adjustable multiresistance, weak ion migration effect and greatly enhanced device stability. Voltage regulation is a promising engineering technique for developing advanced perovskite optoelectronic devices.
Perovskite devices: Digital memories thrive by tuning out defects Innovative materials gaining favor as replacements for silicon solar cells can also be transformed into memory logic circuits using a new fabrication procedure. Lead halide perovskites can be turned into optoelectronic devices through low-cost solution depositions, but these approaches often leave numerous charge-trapping defects in the perovskite. Weili Yu from China’s Changchun Institute of Optics and colleagues have now developed a technique for modifying the defect population of perovskite crystals without requiring chemical additives. The team used probes to apply an electric field to the surface of a perovskite sample for helping move injected charges into defect sites with a high degree of control, which further modulated the optical and electrical properties of perovskite sample. Optimized defect populations enabled the perovskite to act as memristor device, capable of activating multiple resistance states.