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Field-induced ionic motions in all-inorganic CsPbBr3 perovskite quantum dots (QDs) strongly dictate not only their electro-optical characteristics but also the ultimate optoelectronic device performance. Here, we show that the functionality of a single Ag/CsPbBr3/ITO device can be actively switched on a sub-millisecond scale from a resistive random-access memory (RRAM) to a light-emitting electrochemical cell (LEC), or vice versa, by simply modulating its bias polarity. We then realize for the first time a fast, all-perovskite light-emitting memory (LEM) operating at 5 kHz by pairing such two identical devices in series, in which one functions as an RRAM to electrically read the encoded data while the other simultaneously as an LEC for a parallel, non-contact optical reading. We further show that the digital status of the LEM can be perceived in real time from its emission color. Our work opens up a completely new horizon for more advanced all-inorganic perovskite optoelectronic technologies., Electric field induced ion migration is a well-known phenomenon in perovskite, but the consequences are notorious, and thus needs to be prevented. Here, on the other hand, the authors cleverly manipulate this event for realising resistive random-access memory and light-emitting electrochemical cell in one device based on CsPbBr3 quantum dots.

High-density colloidal quantum dot (QD) thin films are promising materials for optoelectronic devices. Our experimental data revealed a unique layer number-dependent photoluminescence (PL) from mul...

We demonstrate a flexible transmissive color filter based on a hybrid metallic–optical Tamm state device composed of a thin metallic film on top of dual dielectric distributed Bragg reflectors (DBR...

Size control is critical in the synthesis of quantum-confined semiconductor nanocrystals, otherwise known as quantum dots. The achievement of size-uniformity and narrow spectral line-width in quantum dots conventionally relies on a very precise kinetic control of the reactions, where reaction time plays a significant role in defining the final crystal sizes and distribution. Here, we show that synthesis of quantum-confined perovskite nanostrips could be achieved through a thermodynamically controlled reaction, using a low-temperature and ligand-rich approach. The nanostrip growth proceeds through an initial one-dimensional (1D) nanorod stage, followed by the lateral widening of the rod to form a two-dimensional (2D) nanostrip. The spectral characteristics of the final product remain unchanged after prolonged reaction, indicating no signs of crystal ripening and confirming the thermodynamic nature of this reaction. The CsPbBr3 perovskite nanostrips were highly uniform and emit at a deep-blue wavelength of 462 nm with a remarkably narrow line-width of 13 nm. This corresponds to color coordinates of (0.136, 0.049) on the CIE 1931 color space, which fulfils the stringent Rec. 2020 standard for next-generation color displays. The well-passivated nanostrips also possess negligible defects and provide a near-unity photoluminescence quantum yield at 94%. Crucially, the achievement of blue emission through a pure-halide perovskite circumvents the problems of spectral instability that are frequently experienced in mixed-halide perovskite systems. The convenience and scalability of our thermodynamic approach, coupled with the excellent optical attributes, would likely enable these quantum-confined perovskite systems to be the preferred method toward color control in trichromatic display applications.

Homogeneously self-assembled colloidal semiconductor quantum dot monolayers (QD-SAMs) over large areas are promising materials for thin film optoelectronic device applications, especially for displ...

Field-induced ionic motions in all-inorganic CsPbBr3 perovskite quantum dots (QDs) strongly dictate not only their electro-optical characteristics but also the ultimate device performance of the CsPbBr3 optoelectronics. Novel device concepts with multiple functionalities can as a result be achieved based on CsPbBr3 by carefully controlling the ionic flow under different bias conditions. Here, we show that by manipulating the ion migrations in two nominally identical, series-connected Ag/CsPbBr3/ITO devices, one device can operate as a resistive random-access memory (RRAM) while the other simultaneously as a light-emitting electrochemical cell (LEC), or vice versa, simply through the polarity switching of the external bias across the entire structure. We further show that this electrically switchable, series-connected perovskite memories and light emitters can be employed as a novel all-perovskite light-emitting memory (LEM) device for simultaneous electronic and optical reading of the encoded information in communication and computation applications. We present a physical picture that clearly depicts the movements of each ionic species and their reduction or oxidation processes in the perovskite LEM responsible for the observed electronic and optical characteristics. The demonstrated bifunctionality of the simple metal-perovskite-metal structures and the novel device concept derived from their creative synergy opens up a completely new horizon for more advanced all-inorganic perovskite optoelectronics with novel functionalities.

Size control is critical in the synthesis of quantum-confined semiconductor nanocrystals, otherwise known as quantum dots. The achievement of size-uniformity and narrow spectral line-width in quantum dots conventionally relies on a very precise kinetic control of the reactions, where reaction time plays a significant role in defining the final crystal sizes and distribution. Here, we show that synthesis of quantum-confined perovskite nanostrips could be achieved through a thermodynamically controlled reaction, using a low-temperature and ligand-rich approach. The nanostrip growth proceeds through an initial one-dimensional (1D) nanorod stage, followed by the lateral widening of the rod to form a two-dimensional (2D) nanostrip. The spectral characteristics of the final product remain unchanged after prolonged reaction, indicating no signs of crystal ripening and confirming the thermodynamic nature of this reaction. The CsPbBr