All‐inorganic colloidal cesium lead halide perovskite quantum dots (CsPbX3, X = Cl, Br, I) are revealed to be a new class of favorable optical‐gain materials, which show ­combined merits of both colloidal quantum dots and halide perovskites. Low‐threshold and ­ultrastable stimulated emission is ­demonstrated under atmospheric conditions with wavelength tunability across the whole ­visible spectrum via either size or composition control.

Novel quantum‐dot light‐emitting diodes based on all‐inorganic perovskite CsPbX3 (X = Cl, Br, I) nanocrystals are reported. The well‐dispersed, single‐crystal quantum dots (QDs) exhibit high quantum yields, and tunable light emission wavelength. The demonstration of these novel perovskite QDs opens a new avenue toward designing optoelectronic devices, such as displays, photodetectors, solar cells, and lasers.

Understanding the growth behavior of nanocrystals (NCs), especially when heteroatoms are introduced, is very important for the optimization of doping (or alloying) and optoelectronic performances. Here, it is reported on the observation of alloying‐facilitated self‐assembly of MgZnO NCs and the underlying mechanism of alloying concentration‐dependent surface grafting. Using the developed one‐pot thermolysis of Zn and Mg organic salts with the help of oleylamine (OAm) and oleic acid (OA), the Mg ions can be introduced into the ZnO lattice without phase separation with concentrations as high as 20%. Interestingly, with the increase of Mg alloying concentration, the morphologies of the products transform from monodispersed NCs to nanoflowers, and then nanobouquet superstructures, which have quasi‐monocrystal features and obey the oriented attachment rules. According to the analyses of surface functional groups, a mechanism involving concentration‐dependent surface grafting is proposed for such alloying‐facilitated self‐assembly.

Transparent electrodes (TEs) are crucial in a wide range of modern electronic and optoelectronic devices. However, traditional TEs cannot meet the requirements of smart devices under development in unique fields, such as electronic skins, wearable electronics, robotic skins, flexible and stretchable displays, and solar cells. Emerging TEs printed with nanocrystal (NC) inks are inexpensive and compatible with solution processes, and have huge potential in flexible, stretchable, and wearable devices. Every development in ink‐based electrodes makes them more competitive for practical applications in various smart devices. Herein, we provide an overview of emergent ink‐based electrodes, such as transparent conducting oxides, metal nanowires, graphene, and carbon nanotubes, and their application in solution‐based flexible and stretchable devices.

As new members of carbon material family, carbon and graphene quantum dots (CDs, GQDs) have attracted tremendous attentions for their potentials for biological, optoelectronic, and energy related applications. Among these applications, bio‐imaging has been intensively studied, but optoelectronic and energy devices are rapidly rising. In this Feature Article, recent exciting progresses on CD‐ and GQD‐based optoelectronic and energy devices, such as light emitting diodes (LEDs), solar cells (SCs), photodetctors (PDs), photocatalysis, batteries, and supercapacitors are highlighted. The recent understanding on their microstructure and optical properties are briefly introduced in the first part. Some important progresses on optoelectronic and energy devices are then addressed as the main part of this Feature Article. Finally, a brief outlook is given, pointing out that CDs and GQDs could play more important roles in communication‐ and energy‐functional devices in the near future.