ganic CsPbX 3 QDs possess narrow full width at half maximum (FWHM) of emission (as small as 12 nm) and excellent quantum yield (QY: 50-90%). [1,8] They have a Bohr diameter up to 12 nm, [1] exhibiting a size-tunable bandgap in the visible region. It is also notable that the exchange of halide ions (Cl − , Br − , and I − ) in as-synthesized perovskite QDs is highly effective, rendering easy and rapid access to a wide range of perovskite QDs with tunable absorption and photoluminescence (PL) spectra. [1] In spite of significant advances in perovskite research noted above, a key to the success of perovskite-based materials and devices is the stability of perovskites as they are susceptible to decomposition due to their ionic crystal nature. [7,9] Recently, several methods including coating with alumina by atomic layer deposition, [10] partial coating with SiO 2 via sol-gel process, [11] physical mixing with hydrophobic polymers, [12] and encapsulation within mesoporous silica [7] or polymer beads [13] have proven to be effective in improving stability in polar and ambient environments. However, nearly all approaches described above for stability enhancement result in nanocomposites with multiple perovskite QDs encapsulated in microscopic protective matrices. These microscale nanocomposites may be disadvantageous for biomedical applications where cellular uptake is more feasible for smaller nanoscopic particles, [14] or LEDs where the processing of nanoscopic luminescent particles often leads to low scattering loss, higher loading and packing density, and thus film uniformity. [11] Clearly, the ability to deliberately and reliably improve the stability of perovskite QDs (e.g., against humidity and polar solvents) while retaining their individual nanometer size represents a critical step that underpins future advances in optoelectronic and biological applications.Herein, we report a general and robust strategy by capitalizing on judiciously designed amphiphilic star-like diblock copolymers with well-controlled molecular weight and low polydispersity of each block as molecularly engineered nanoreactors to craft uniform perovskite QDs. Remarkably, these QDs simultaneously possess precisely tunable dimensions Instability of perovskite quantum dots (QDs) toward humidity remains one of the major obstacles for their long-term use in optoelectronic devices. Herein, a general amphiphilic star-like block copolymer nanoreactor strategy for in situ crafting a set of hairy perovskite QDs with precisely tunable size and exceptionally high water and colloidal stabilities is presented. The selective partition of precursors within the compartment occupied by inner hydrophilic blocks of star-like diblock copolymers imparts in situ formation of robust hairy perovskite QDs permanently ligated by outer hydrophobic blocks via coprecipitation in nonpolar solvent. These size-and compositiontunable perovskite QDs reveal impressive water and colloidal stabilities as the surface of QDs is intimately and permanently ligated by a layer of outer ...

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Homogeneous and high-quality GaN films with a RMS thickness inhomogeneity of less than 2.8% were grown on an AlN buffer layer using pulsed laser deposition and optimized laser rastering program.

Interfacial engineering represents a critical step towards passivating trap states and facilitating charge transfer across interfaces in perovskite photovoltaics, thereby resulting in substantially improved device performance. Herein, we report on...

We demonstrate the fabrication of highly-efficient GaAs/graphene Schottky junction solar cells by interfacial modification with a self-assembled alkyl thiol monolayer.

The size-controllable and ordered Au nanostructures were achieved by applying the self-assembled monolayer of polystyrene microspheres. Few-layer graphene was transferred directly on top of Au nanostructures, and the coupling between graphene and the localized surface plasmons (LSPs) of Au was investigated. We found that the LSP resonance spectra of ordered Au exhibited a redshift of ~20 nm and broadening simultaneously by the presence of graphene. Meanwhile, the surface-enhanced Raman spectroscopy (SERS) of graphene was distinctly observed; both the graphene G and 2D peaks increased induced by local electric fields of plasmonic Au nanostructures, and the enhancement factor of graphene increased with the particle size, which can be ascribed to the plasmonic coupling between the ordered Au LSPs and graphene.

The effects of the thickness of the large-mismatched amorphous In 0.6 Ga 0.4 As buffer layer on In 0.3 Ga 0.7 As epi-films grown on a GaAs substrate have been systematically investigated. The In 0.3 Ga 0.7 As films with the In 0.6 Ga 0.4 As buffer layer of 0, 1, 2, and 4 nm thickness are grown by low-temperature molecular beam epitaxy (LT-MBE) and are characterized by X-ray diffraction (XRD) and transmission electron microscopy (TEM). It is found that the degree of relaxation and the crystallinity of the as-grown In 0.3 Ga 0.7 As films are strongly affected by the thickness of the amorphous In 0.6 Ga 0.4 As buffer layer. The thinner In 0.6 Ga 0.4 As buffer layer is not enough to efficiently release the misfit strain between the In 0.3 Ga 0.7 As epilayer and the GaAs substrate, while the thicker In 0.6 Ga 0.4 As buffer layer is unfavorable to trap the dislocations and prevent them from extending into the In 0.3 Ga 0.7 As epi-films. We have demonstrated that the amorphous In 0.6 Ga 0.4 As buffer layer with a thickness of 2 nm can advantageously prevent threading and misfit dislocations from propagating into the subsequent In 0.3 Ga 0.7 As epilayer and increase the degree of relaxation of the as-grown In 0.3 Ga 0.7 As, ultimately leading to a high-quality In 0.3 Ga 0.7 As film. Our novel buffer layer technology has triggered a simple but effective approach to grow high-crystallinity In 0.3 Ga 0.7 As epitaxial film and is favorable for fabrication of GaAs-based high-efficiency four-junction solar cells.