Device performance and in particular device stability for blue perovskite light-emitting diodes (PeLEDs) remain considerable challenges for the whole community. In this manuscript, we conceive an approach by tuning the ‘A-site’ cation composition of perovskites to develop blue-emitters. We herein report a Rubidium-Cesium alloyed, quasi-two-dimensional perovskite and demonstrate its great potential for pure-blue PeLED applications. Composition engineering and in-situ passivation are conducted to further improve the material’s emission property and stabilities. Consequently, we get a prominent film photoluminescence quantum yield of around 82% under low excitation density. Encouraged by these findings, we finally achieve a spectra-stable blue PeLED with the peak external quantum efficiency of 1.35% and a half-lifetime of 14.5 min, representing the most efficient and stable pure-blue PeLEDs reported so far. The strategy is also demonstrated to be able to generate efficient perovskite blue emitters and PeLEDs in the whole blue spectral region (from 454 to 492 nm).

Rapid Auger recombination represents an important challenge faced by quasi-2D perovskites, which induces resulting perovskite light-emitting diodes’ (PeLEDs) efficiency roll-off. In principle, Auger recombination rate is proportional to materials’ exciton binding energy (Eb). Thus, Auger recombination can be suppressed by reducing the corresponding materials’ Eb. Here, a polar molecule, p-fluorophenethylammonium, is employed to generate quasi-2D perovskites with reduced Eb. Recombination kinetics reveal the Auger recombination rate does decrease to one-order-of magnitude lower compared to its PEA+ analogues. After effective passivation, nonradiative recombination is greatly suppressed, which enables resulting films to exhibit outstanding photoluminescence quantum yields in a broad range of excitation density. We herein demonstrate the very efficient PeLEDs with a peak external quantum efficiency of 20.36%. More importantly, devices exhibit a record luminance of 82,480 cd m−2 due to the suppressed efficiency roll-off, which represent one of the brightest visible PeLEDs yet.

Organic–inorganic hybrid halide perovskite solar cells (PSCs) have recently drawn enormous attentions due to their impressive performance (>22%) and low temperature solution processability (<150 °C). Current solution process involves application of a large amount of toxic solvents, such as chlorobenzene, which is heavily employed in both the perovskite layer and the hole transport layer (HTL) deposition. Herein, this study employs green solvent of ethyl acetate for engineering efficient perovskite and HTL layers, which enables a synergic interface (perovskite/HTL) optimization. A champion efficiency of 19.43% is obtained for small cells (0.16 cm2 with mask) and over 14% for large size modules (5 × 5 cm2). The PSCs prepared from the green solvent engineering demonstrate superior performance on both efficiency and stability over their chlorobenzene counterparts. These enhancements are ascribed to the in situ inhibition on carrier recombination induced by interfacial defects during the solution processing, which enables about 2/3 reduction of calculated recombination rate. Thus, the green solvent route shows the great potential toward environmental‐friendly manufacturing.

Reduced-dimensional (quasi-2D) perovskite materials are widely applied for perovskite photovoltaics due to their remarkable environmental stability. However, their device performance still lags far behind traditional three dimensional perovskites, particularly high open circuit voltage (V oc) loss. Here, inhomogeneous energy landscape is pointed out to be the sole reason, which introduces extra energy loss, creates band tail states and inhibits minority carrier transport. We thus propose to form homogeneous energy landscape to overcome the problem. A synergistic approach is conceived, by taking advantage of material structure and crystallization kinetic engineering. Accordingly, with the help of density functional theory guided material design, (aminomethyl) piperidinium quasi-2D perovskites are selected. The lowest energy distribution and homogeneous energy landscape are achieved through carefully regulating their crystallization kinetics. We conclude that homogeneous energy landscape significantly reduces the Shockley-Read-Hall recombination and suppresses the quasi-Fermi level splitting, which is crucial to achieve high V oc .

Serious performance decline arose for perovskite light-emitting diodes (PeLEDs) once the active area was enlarged. Here we investigate the failure mechanism of the widespread active film fabrication method; and ascribe severe phase-segregation to be the reason. We thereby introduce L-Norvaline to construct a COO−-coordinated intermediate phase with low formation enthalpy. The new intermediate phase changes the crystallization pathway, thereby suppressing the phase-segregation. Accordingly, high-quality large-area quasi-2D films with desirable properties are obtained. Based on this, we further rationally adjusted films’ recombination kinetics. We reported a series of highly-efficient green quasi-2D PeLEDs with active areas of 9.0 cm2. The peak EQE of 16.4% is achieved in <n > = 3, represent the most efficient large-area PeLEDs yet. Meanwhile, high brightness device with luminance up to 9.1 × 104 cd m−2 has achieved in <n> = 10 film.

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Aqueous zinc‐ion batteries (ZIBs) are considered to be a promising candidate for flexible energy storage devices due to their high safety and low cost. However, the scalable assembly of flexible ZIBs is still a challenge. Here, a scalable assembly strategy is developed to fabricate flexible ZIBs with an ultrathin all‐in‐one structure by combining blade coating with a rolling assembly process. Such a unique all‐in‐one integrated structure can effectively avoid the relative displacement or detachment between neighboring components to ensure continuous and effective ion‐ and/or loading‐transfer capacity under external deformation, resulting in excellent structural and electrochemical stability. Furthermore, the ultrathin all‐in‐one ZIBs can be tailored and edited controllably into desired shapes and structures, further extending their editable, stretchable, and shape‐customized functions. In addition, the ultrathin all‐in‐one ZIBs display the ability to integrate with perovskite solar cells to achieve an energy harvesting and storage integrated system. These enlighten a broad area of flexible ZIBs to be compatible with highly flexible and wearable electronics. The scaling‐up assembly strategy provides a route to design other ultrathin all‐in‐one energy storage devices with stretchable, editable, and customizable behaviors.

BackgroundChimeric antigen receptor-engineered T (CAR-T) cells have extraordinary effect in treating lymphoblastic leukemia. However, treatment of acute myeloid leukemia (AML) using CAR-T cells remains limited to date. Leukemogenesis always relates with the abnormalities of cytogenetics, and nearly one third of AML patients have activating mutations in Fms-like tyrosine kinase 3 (FLT3) which reminded poor prognosis. Considering the FLT3 expressed in AML patients’ blast cells, it may be a new candidate target for CAR-T therapy to treat FLT3+ AML, especially patients harboring FLT3-ITD mutation.MethodsThe FLT3L CAR-T using FLT3 ligand as recognizing domain was constructed. The specific cytotoxicity against FLT3+ leukemia cell lines, primary AML cells, and normal hematopoietic progenitor stem cells (HPSCs) in vitro were evaluated. In addition, FLT3+ AML mouse model was used to assess the effect of FLT3L CAR-T therapy in vivo.ResultsFLT3L CAR-T cells could specifically kill FLT3+ leukemia cell lines and AML patients’ bone marrow mononuclear cells in vitro (with or without FLT3 mutation) and have more potent cytotoxicity to FLT3-ITD cells. In a human FLT3+ AML xenograft mouse model, FLT3L CAR-T cells could significantly prolong the survival of mice. Furthermore, it was found that FLT3L CAR-T cells could activate the FLT3/ERK signaling pathway of FLT3+ leukemia cells with wild-type FLT3; meanwhile, it had no inhibitory effects on the colony formation of CD34+ stem cells derived from normal human umbilical cord blood.ConclusionsThe ligand-based FLT3L CAR-T cells could be a promising strategy for FLT3+ AML treatment, especially those carried FLT3 mutation.Electronic supplementary materialThe online version of this article (10.1186/s13045-018-0603-7) contains supplementary material, which is available to authorized users.