In many years, the Ministry of Science and Technology has been encouraging the scientific research. This research plan is under the long-term support of the Ministry of Science and Technology, National Taiwan Normal University Prof. Ya-Ju Lee and Kyushu University Prof. Kaoru Tamada have developed a new device that needs only a single semiconductor known as perovskite to simultaneously store and visually transmit data. This outstanding fundamental research result was published in the top journal ⟪ Nature Communications⟫ in 2021.
At the most fundamental level, digital data is stored as a basic unit of information known as a bit, which is often represented as either a one or a zero. Thus, the pursuit of better data storage comes down to finding more efficient ways to store and read these ones and zeros. While flash memory has become extremely popular, researchers have been searching for alternatives that could further improve speed and simplify fabrication. One candidate is nonvolatile resistive random-access memory, or RRAM. Instead of storing charge in transistors like in flash memory, resistive memory uses materials that can switch between states of high and low resistance to represent ones and zeros.
However, previous versions of light-emitting memories required the integration of two separate devices with differing materials, complicating fabrication. To overcome this, the researchers turned to perovskite, a type of material with a crystalline structure through which ions can migrate to give it unique physical, optical, and even electrical properties. By controlling the ion migration, perovskite researchers have been constructing new materials with unique properties. Using perovskite consisting of cesium lead bromide (CsPbBr3), the team demonstrated that data can be electrically written, erased, and read in one of the perovskite devices acting as an RRAM. Simultaneously, the second perovskite device can optically transmit whether data is being written or erased through light emission by working as a light-emitting electrochemical cell with a high transmission speed. Furthermore, the researchers used perovskite quantum dots of two different sizes for the two devices in the light-emitting memory to achieve different emission colors depending on whether the memory was being written or erased, providing a real-time indicator of the ones and zeros.
This demonstration significantly broadens the scope of applications of the developed all-perovskite light-emitting memory and can serve as a new paradigm of synergistic combination between electronic and photonic degrees of freedom in perovskite materials. From multicast mesh network to data encryption systems, these findings have the potential for numerous applications in next-generation technologies.
Dr. Ya-Ju Lee, Professor, Institute and Undergraduate program of electro-optical engineering, National Taiwan Normal University