Control over morphology and crystallinity of metal halide perovskite films is of key importance to enable high-performance optoelectronics. However, this remains particularly challenging for solution-printed devices due to the complex crystallization kinetics of semiconductor materials within dynamic flow of inks. Here we report a simple yet effective meniscus-assisted solution printing (MASP) strategy to yield large-grained dense perovskite film with good crystallization and preferred orientation. Intriguingly, the outward convective flow triggered by fast solvent evaporation at the edge of the meniscus ink imparts the transport of perovskite solutes, thus facilitating the growth of micrometre-scale perovskite grains. The growth kinetics of perovskite crystals is scrutinized by in situ optical microscopy tracking to understand the crystallization mechanism. The perovskite films produced by MASP exhibit excellent optoelectronic properties with efficiencies approaching 20% in planar perovskite solar cells. This robust MASP strategy may in principle be easily extended to craft other solution-printed perovskite-based optoelectronics.

The ability to synthesize a diverse spectrum of one-dimensional (1D) nanocrystals presents an enticing prospect for exploring nanoscale size- and shape-dependent properties. Here we report a general strategy to craft a variety of plain nanorods, core-shell nanorods, and nanotubes with precisely controlled dimensions and compositions by capitalizing on functional bottlebrush-like block copolymers with well-defined structures and narrow molecular weight distributions as nanoreactors. These cylindrical unimolecular nanoreactors enable a high degree of control over the size, shape, architecture, surface chemistry, and properties of 1D nanocrystals. We demonstrate the synthesis of metallic, ferroelectric, upconversion, semiconducting, and thermoelectric 1D nanocrystals, among others, as well as combinations thereof.

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Extending the spectral absorption of organolead halide perovskite solar cells from visible into near-infrared (NIR) range renders the minimization of non-absorption loss of solar photons with improved energy alignment. Herein, we report on, for the first time,aviable strategy of capitalizing on judiciously synthesized monodisperse NaYF 4 :Yb/Er upconversion nanoparticles (UCNPs) as the mesoporous electrode for CH 3 NH 3 PbI 3 perovskites olar cells and more importantly confer perovskites olar cells to be operative under NIR light. Uniform NaYF 4 :Yb/Er UCNPs are first crafted by employing rationally designed double hydrophilic star-like poly(acrylic acid)-block-poly(ethylene oxide) (PAA-b-PEO) diblock copolymer as nanoreactor,i mparting the solubility of UCNPs and the tunability of film porosity during the manufacturing process.T he subsequent incorporation of NaYF 4 :Yb/Er UCNPs as the mesoporous electrode led to ah igh efficiency of 17.8 %, which was further increased to 18.1 %u pon NIR irradiation. The in situ integration of upconversion materials as functional components of perovskite solar cells offers the expanded flexibility for engineering the device architecture and broadening the solar spectral use.

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 ...

Well-controlled nanostructures and a high fraction of Sn/Li O interface are critical to enhance the coulombic efficiency and cyclic performance of SnO -based electrodes for lithium-ion batteries (LIBs). Polydopamine (PDA)-coated SnO nanocrystals, composed of hundreds of PDA-coated "corn-like" SnO nanoparticles (diameter ca. 5 nm) decorated along a "cob", addressed the irreversibility issue of SnO -based electrodes. The PDA-coated SnO were crafted by capitalizing on rationally designed bottlebrush-like hydroxypropyl cellulose-graft-poly (acrylic acid) (HPC-g-PAA) as a template and was coated with PDA to construct a passivating solid-electrolyte interphase (SEI) layer. In combination, the corn-like nanostructure and the protective PDA coating contributed to a PDA-coated SnO electrode with excellent rate capability, superior long-term stability over 300 cycles, and high Sn→SnO reversibility.

The past few years have witnessed rapid advances in the synthesis of high-quality perovskite nanocrystals (PNCs). However, despite the impressive developments, the stability of PNCs remains a substantial challenge. The ability to reliably improve stability of PNCs while retaining their individual nanometer size represents a critical step that underpins future advances in optoelectronic applications. Here, we report an unconventional strategy for crafting dual-shelled PNCs (i.e., polymer-ligated perovskite/SiO2 core/shell NCs) with exquisite control over dimensions, surface chemistry, and stabilities. In stark contrast to conventional methods, our strategy relies on capitalizing on judiciously designed star-like copolymers as nanoreactors to render the growth of core/shell NCs with controlled yet tunable perovskite core diameter, SiO2 shell thickness, and surface chemistry. Consequently, the resulting polymer-tethered perovskite/SiO2 core/shell NCs display concurrently a stellar set of substantially improved stabilities (i.e., colloidal stability, chemical composition stability, photostability, water stability), while having appealing solution processability, which are unattainable by conventional methods.

Three-dimensional (3D) interconnected metal alloy nanostructures possess superior catalytic performance owing to their advantageous characteristics, including improved catalytic activity, corrosion resistance, and stability. Hierarchically structured Ni-Cu alloys composed of 3D network-like microscopic branches with nanoscopic dendritic feelers on each branch were crafted by a facile and efficient hydrogen evolution-assisted electrodeposition approach. They were subsequently exploited for methanol electrooxidation in alkaline media. Among three hierarchically structured Ni-Cu alloys with different Ni/Cu ratios (Ni Cu , Ni Cu , and Ni Cu ), the Ni Cu electrode exhibited the fastest electrochemical response and highest electrocatalytic activity toward methanol oxidation. The markedly enhanced performance of Ni Cu eletrocatalyst can be attributed to its alloyed structure with the proper Ni/Cu ratio and a large number of active sites on the surface of hierarchical structures.