Transfer-Imprinting-Assisted Growth of 2D/3D Perovskite Heterojunction for Efficient and Stable Flexible Inverted Perovskite Solar Cells.

2D/3D perovskite heterostructures show great potential to boost efficiency and stability of perovskite solar cells (PSCs). Here, a solvent-free transfer-imprinting-assisted growth (TIAG) method is employed to in situ grow 2D/3D perovskite heterojunctions. The solid-state transfer of spacer cation by the TIAG process enables a spatially confined growth of the 2D perovskite interlayer with uniform morphology between the 3D perovskites and charge transport layer. Meanwhile, the pressure associated with the TIAG process promotes the crystalline orientation, which is beneficial to carrier transport. As a result, the inverted PSC achieved a PCE of 23.09% (with certified 22.93%) and maintained 90% of their initial PCE after aging at 85 °C for 1200 h or operating for 1100 h under continuous AM 1.5 illumination. Flexible inverted PSCs achieved a PCE of 21.14% with mechanical robustness by maintaining above 80% of their initial PCE after 10000 bending cycles under a 3 mm bending radius.

High-Resolution Patterning of Perovskite Quantum Dots via Femtosecond Laser-Induced Forward Transfer.

High-resolution patterning of perovskite quantum dots (PQDs) is of significant importance for satisfying various practical applications, including high-resolution displays and image sensing. However, due to the limitation of the instability of PQDs, the existing patterning strategy always involves chemical reagent treatment or mask contact that is not suitable for PQDs. Therefore, it is still a challenge to fabricate high-resolution full-color PQD arrays. Here, we present a femtosecond laser-induced forward transfer (FsLIFT) technology, which enables the programmable fabrication of high-resolution full-color PQD arrays and arbitrary micropatterns. The FsLIFT process integrates transfer, deposition, patterning, and alignment in one step without involving a mask and chemical reagent treatment, guaranteeing the preservation of the photophysical properties of PQDs. A full-color PQD array with a high resolution of 2 µm has been successfully achieved. We anticipate that our facile and flexible FsLIFT technology can facilitate the development of diverse practical applications based on patterned PQDs.

Nanoscale control of non-reciprocal ripple writing.

Femtosecond laser-induced deep-subwavelength structures have attracted much attention as a nanoscale surface texturization technique. A better understanding of the formation conditions and period control is required. Herein, we report a method of non-reciprocal writing via a tailored optical far-field exposure, where the period of ripples varies along different scanning directions, and achieve a continuous manipulation of the period from 47 to 112 nm (±4 nm) for a 100-nm-thick indium tin oxide (ITO) on glass. A full electromagnetic model was developed to demonstrate the redistributed localized near-field at different stages of ablation with nanoscale precision. It explains the formation of ripples and the asymmetry of the focal spot determines the non-reciprocity of ripple writing. Combined with beam shaping techniques, we achieved non-reciprocal writing (regarding scanning direction) using an aperture-shaped beam. The non-reciprocal writing is expected to open new paths for precise and controllable nanoscale surface texturing.

Optical near fields for ablation of periodic structures.

The formation mechanism of laser-induced periodic surface structures (LIPSS) has been a key to high-resolution sub-diffraction lithography or high-efficiency large-area nanotexturing. We show the evolution of LIPSS formation from a nanohole seed structure to high-spatial-frequency LIPSS by using a tightly focused and rectangular-shaped laser beam with different shape-polarization orientations. Formation of LIPSS based on light intensity distribution without invoking any long-range electromagnetic modes achieved quantitative match between modeling and experiment. Our results clearly show the entire step-like and deterministic process of LIPSS evolution based on experimental data and numerical simulations, revealing the dominant structural near-field enhancement on the ripple formation. A rectangular-shaped beam with an aspect ratio of 7:3 was used to break the symmetry of a circularly shaped focus. By azimuthally rotating the orientation of the focal spot and the polarization, it is possible to visualize the far-field effect for the initial seed structure formation and the competition between the far and near fields in the subsequent structure evolution.

Overexpression of SH2D1A promotes cancer progression and is associated with immune cell infiltration in hepatocellular carcinoma via bioinformatics and in vitro study.

BACKGROUND: SH2 domain containing 1A (SH2D1A) expression has been linked to cancer progression. However, the functions of SH2D1A in hepatocellular carcinoma (HCC) have not been reported. METHODS: The effects of SH2D1A on the proliferation, migration, and invasion of HCC cells and the related pathways were re-explored in cell models with SH2D1A overexpression using the CCK-8, migration and invasion assays and western blotting. The functions and mechanisms of genes co-expressed with SH2D1A were analyzed using gene ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis. The relationship between SH2D1A expression and immune microenvironment features in HCC was explored. RESULTS: Elevated SH2D1A expression promoted cell proliferation, migration, and invasion, which was related to the overexpression of p-Nf-κB and BCL2A1 protein levels in HCC. SH2D1A expression was related to the immune, stromal, and ESTIMATE scores, and the abundance of immune cells, such as B cells, CD8+ T cells, and T cells. SH2D1A expression was significantly related to the expression of immune cell markers, such as PDCD1, CD8A, and CTLA4 in HCC. CONCLUSION: SH2D1A overexpression was found to promote cell growth and metastasis via the Nf-κB signaling pathway and may be related to the immune microenvironment in HCC. The findings indicate that SH2D1A can function as a biomarker in HCC.

Improved Performance of All-Inorganic Perovskite Light-emitting Diodes via Nanostructured Stamp Imprinting.

Halide perovskites are emerging emitters with excellent optoelectronic properties. Contrary to the large grain fabrication goal in perovskite solar cells, perovskite light-emitting diodes (PeLEDs) based on small grain enable efficient radiative recombination because of relatively higher charge carrier densities due to spatial confinement. However, achieving small-sized grain growth with superior crystal quality and film morphology remains a challenge. In this work, we demonstrated a nanostructured stamp thermal imprinting strategy to boost the surface coverage and improve the crystalline quality of CsPbBr3 film, particularly confine the grain size, leading to the improvement of luminance and efficiency of PeLEDs. We improved the thermal imprinting process utilizing the nanostructured stamp to selectively manipulate the nucleation and growth in the nanoscale region and acquire small-sized grain accompanied by improved crystal quality and surface morphology of the film. By optimizing the imprinting pressure and the period of the nanostructures, appropriate grain size, high surface coverage, small surface roughness and improved crystallization could be achieved synchronously. Finally, the maximum luminance and efficiency of PeLEDs achieved by nanostructured stamp imprinting with a period of 320 nm are 67600 cd/m2 and 16.36 cd/A, respectively. This corresponds to improvements of 123 % in luminance and 100 % in efficiency, compared to that of PeLEDs without the imprinting.

Efficient all-inorganic red perovskite light-emitting diodes with dual-interface-modified perovskites by vapor deposition.

Interface engineering has been extensively used in perovskite light-emitting diodes (PeLEDs), which proves to be an effective and intelligent approach for surface defect passivation. However, the existing passivation strategy is restricted to the solution process, which results in poor compatibility with vapor-deposited PeLEDs and moderate controllability. Here, we propose a dual-interface modification strategy to facilitate the performance improvement of vapor-deposited all-inorganic red PeLEDs. An ultrathin phenylethanamine bromide (PEABr) layer is introduced to both the upper and lower interfaces of the vapor-deposited perovskite emission layer by vapor deposition. The vapor deposition of the PEABr with fine-controlled film thickness is a reliable and simple process and compatible with vapor-deposited all-inorganic PeLEDs. The dual-interface modification plays an observable role in manipulating the crystallization and surface morphology of the CsPbBrI2 film, which is of significance for the improvement of the PeLEDs' performance. As a result, the red PeLEDs achieve a maximum luminance and external quantum efficiency of 2338 cd/m2 and 1.75%, corresponding to enhancements of 2.75 and 5.25 times compared with those of PeLEDs without PEABr. This approach paves the way to high-efficiency all-evaporated all-inorganic PeLEDs.

Nucleation in situ of perylene crystal by femtosecond laser induced cavitation.

Organic semiconductor single crystal materials have broad application prospects in the field of high-performance optoelectronic devices because of their highly ordered structure, few defects, and high carrier mobility. However, it is difficult to control the nucleation location of crystal formation in the current commonly used crystal growth methods including physical vapor transport and solution processing, which makes it difficult to manufacture organic crystal devices. Laser-induced crystallization technology is expected to solve this problem. In this study, we demonstrated nucleation in situ of a perylene crystal by femtosecond laser induced cavitation. The results show that the crystallization of perylene crystals induced by the femtosecond laser is mainly due to the aggregation effect by laser cavitation bubbles caused by multiphoton absorption. This strategy facilitates the application of organic single crystals to optoelectronic devices.

Spatially modulated light harvesting with plasmonic crescent metasurface.

Harvesting light by metallic structures with sharp corners, or the so-called photonic singularities, has exhibit their potential in nanophotonics, sensing, and bio-medical applications. The high-quality light confinement of the light energy mainly relies on the precise preparation of nanoscale photonic singularities. However, the realization of massive photonic singularities still meets the challenges on integration and low-cost mask multiplexing. Here, we show an angle-dependent elevated nanosphere lithography to achieve massive photonic singularities for spatially modulated light harvesting at the near-infrared regime. The photonic geometrical singularity is constructed by the gold crescent array of plasmonic materials. The numerical simulation shows that the light can be localized at the spatially distributed singularities. This phenomenon is verified experimentally through the infrared spectral measurement. Our work provides the possibility to produce integrated light-harvesting devices for numerous optical applications in illumination, display, and enhanced nonlinear excitation.

Efficient and stretchable organic light-emitting devices based on spontaneously formed disordered wrinkles.

We propose a facile, scalable strategy to introduce spontaneously formed disordered wrinkles into organic light-emitting devices (OLEDs) to enhance light extraction and realize stretchability of the devices. The luminance and current efficiency of the wrinkled OLEDs are improved by 37% and 18%, respectively, compared to the planar device. Meanwhile, broadband light scattering induced by the disordered wrinkles results in angle-stable electroluminescent spectra at wide viewing angles for the wrinkled OLEDs. The disordered wrinkles enable the OLEDs to be stretchable and withstand hundreds of stretching-releasing cycles at strain between 0% and 5%. This study provides a simple method to realize stretchable OLEDs with high efficiency.

Omnidirectional light absorption enhancement of perovskite solar cells by an antireflection film with holographic lithography microstructures.

We report an omnidirectional light absorption enhancement of a perovskite solar cell (PSC) using antireflection (AR) film with soft imprinted microstructures from master molds via holographic lithography technology, which has high throughput and repeatability. The PSC's omnidirectional power conversion efficiency (PCE) enhancement is achieved by reducing Fresnel surface reflections and enhancing the optical path length. The maximum PCE of PSCs with AR film is up to 20.27%, corresponding to an absolute increase of 0.93% compared to 19.34% of control devices. Significantly, the enhancements of PCE increase with incident angle enlargement, which attributes to more effective Fresnel surface reflection suppression. Moreover, AR films exhibit water and dust repellent properties due to hydrophobicity, which is beneficial for PSC's long-term stability and light harvesting.

Improved performance of pure red perovskite light-emitting devices based on CsPb(Br1-xIx)3 with variable content of iodine and bromine.

All-inorganic cubic α-CsPbI3 perovskite for red perovskite light-emitting device (PeLED) applications is suffering from a phase transition. Unstable black α phase tends to transit to yellow δ phase under ambient conditions, which results in poor performance of the CsPbI3-based PeLEDs. Partial replacement of iodine anion with a comparatively smaller bromine anion in the perovskite film can effectively adjust the Goldschmidt tolerance factor and stabilize the α-phase. A phase-stable CsPb(Br1-xIx)3 perovskite has been obtained at low annealing temperature of 50°C by tuning the iodine-to-bromine ratios. A PeLED with pure red emission based on the CsPb(Br0.43I0.57)3 perovskite has been demonstrated. The maximum luminance and efficiency were 2200cd/m2 and 0.38 cd/A, respectively. Moreover, the PTAA layer was introduced between the PEDOT:PSS and perovskite film to improve the surface morphologies of perovskite. As a result, red PeLEDs with a maximum luminance of 2765cd/m2 have been achieved.

Enhanced efficiency of organic light-emitting devices by using a directly imprinted nanopillared ultrathin metallic electrode.

An ultrathin metal film with high transmittance and conductivity has been demonstrated to be a promising transparent electrode for organic light-emitting devices (OLEDs). However, mediocre surface morphology and continuity of evaporated metal films and the surface plasmon-polaritons (SPPs) energy loss between the metal electrode and organic layer still limit the external quantum efficiency (EQE) of OLEDs. Here, nanoimprint lithography has been directly applied on the ultrathin Au film with underlying uncured photopolymer to fabricate the nanopillared anode. Both the conductivity and transmittance of the nanopillared ultrathin Au film have been improved due to the improvement of continuity and surface smoothness. As we expected, the SPPs mode has been coupled into photons and further extracted from OLEDs by using the nanopillared Au film anode. Finally, 19.2% and 70.1% enhancement of current efficiency were achieved compared to the planar device with ultrathin Au anode and ITO anode, respectively.

Improved light extraction in all-inorganic perovskite light-emitting devices with periodic nanostructures by nanoimprinting lithography.

We report an improved light extraction in all-inorganic perovskite light-emitting devices (PeLEDs) by integrating a periodic corrugated nanostructure at the metallic cathode/organic interface. Nanoimprinting lithography was used to introduce the nanostructures onto the surface of the electron transport layer directly to avoid influencing the morphology and crystallinity of the perovskite film underneath. The trapped energy at the metallic electrode has been successfully outcoupled by the excitation of the surface plasma polariton (SPP) modes induced by the periodic corrugations. The luminance and current efficiency of the periodically corrugated PeLED exhibit enhancements of 42% and 28%, respectively, compared to those of the planar PeLED. The finite-difference time-domain simulation was used to confirm the efficient outcoupling of the SPP modes.

VAMP3 and SNAP23 mediate the disturbed flow-induced endothelial microRNA secretion and smooth muscle hyperplasia.

Vascular endothelial cells (ECs) at arterial branches and curvatures experience disturbed blood flow and induce a quiescent-to-activated phenotypic transition of the adjacent smooth muscle cells (SMCs) and a subsequent smooth muscle hyperplasia. However, the mechanism underlying the flow pattern-specific initiation of EC-to-SMC signaling remains elusive. Our previous study demonstrated that endothelial microRNA-126-3p (miR-126-3p) acts as a key intercellular molecule to increase turnover of the recipient SMCs, and that its release is reduced by atheroprotective laminar shear (12 dynes/cm2) to ECs. Here we provide evidence that atherogenic oscillatory shear (0.5 ± 4 dynes/cm2), but not atheroprotective pulsatile shear (12 ± 4 dynes/cm2), increases the endothelial secretion of nonmembrane-bound miR-126-3p and other microRNAs (miRNAs) via the activation of SNAREs, vesicle-associated membrane protein 3 (VAMP3) and synaptosomal-associated protein 23 (SNAP23). Knockdown of VAMP3 and SNAP23 reduces endothelial secretion of miR-126-3p and miR-200a-3p, as well as the proliferation, migration, and suppression of contractile markers in SMCs caused by EC-coculture. Pharmacological intervention of mammalian target of rapamycin complex 1 in ECs blocks endothelial secretion and EC-to-SMC transfer of miR-126-3p through transcriptional inhibition of VAMP3 and SNAP23. Systemic inhibition of VAMP3 and SNAP23 by rapamycin or periadventitial application of the endocytosis inhibitor dynasore ameliorates the disturbed flow-induced neointimal formation, whereas intraluminal overexpression of SNAP23 aggravates it. Our findings demonstrate the flow-pattern-specificity of SNARE activation and its contribution to the miRNA-mediated EC-SMC communication.

DNA methyltransferase 1 and Krüppel-like factor 4 axis regulates macrophage inflammation and atherosclerosis.

Macrophage-mediated inflammatory responses occur throughout all stages of atherosclerosis. DNA methylation is one of the critical epigenetic mechanisms and is associated with the development of atherosclerosis. The underlying mechanism of epigenetic regulation of macrophage inflammation (M1 activation) remains unclear. Here we aim to study the role of DNA methyltransferase 1 (DNMT1) in modulating macrophage inflammation and atherosclerosis. DNMT1 expression is up-regulated in THP-1-derived macrophages upon treatment with lipopolysaccharide (LPS) and interferon-gamma (IFN-γ). Overexpression of DNMT1 promotes the LPS- and IFN-γ-induced M1 activation whereas inhibition of DNMT1 attenuates it. Consistently, DNMT1 expression is elevated in macrophages in atherosclerotic plaques from human and mouse specimens; compared with the Dnmt1wild-type, myeloid Dnmt1 deficiency in mice in an Apolipoprotein E (ApoE) knockout background or receiving AAV-PSCK9 injection and carotid partial ligation results in ameliorated atheroma formation and suppressed plaque inflammation. The promoter regions of atheroprotective Krüppel-like factor 4 (KLF4) are hypermethylated in M1- activated macrophages. DNMT1 down-regulates the expression of KLF4, probably through catalyzing DNA methylation of the promoter regions of KLF4. Gain- and loss-of function study of KLF4 indicates that the DNMT1-mediated macrophage M1 activation is dependent on KLF4. Our data demonstrate a proatherogenic role for DNMT1 as a defining factor in macrophage inflammation both in vitro and in vivo. DNMT1 promotes macrophage M1 activation by suppressing KLF4 expression. Thus macrophage-specific DNMT1 inhibition may provide an attractive therapeutic potential to prevent or reduce atherosclerosis.

Enhanced efficiency of all-inorganic perovskite light-emitting diodes by using F4-TCNQ-doped PTAA as a hole-transport layer.

We demonstrate an enhanced efficiency of all-inorganic perovskite light-emitting diodes (PeLEDs) by doping an electron acceptor of 2,3,5,6-tetrafluoro-7,7,8,8-tetracyanoquinodimethane (F4-TCNQ) as a p-type dopant into the hole-transport layer (HTL) of poly-triarylamine (PTAA). The conductivity of the PTAA was improved by the formation of the CT complex through the electron transfer from the PTAA to F4TCNQ. Moreover, the hydrophobic surface of the PTAA leads to an improved surface morphology of the perovskite films compared to that on the conventionally used HTL of PEDOT:PSS. As a result, the maximum luminance and efficiency for the doped PTAA-based PeLEDs are 28020 cd/m2 and 13.5 cd/A, respectively, corresponding to 32.7% and 48% improvement in the efficiency compared to those of the pure PTAA or PEDOT:PSS-based PeLEDs.

Improved Performance and Stability of Quasi-Two-Dimensional Perovskite Solar Cells by Post-treatment with Acetaminophen.

Recently, perovskite solar cells (PSCs) based on quasi-two-dimensional (quasi-2D) perovskites have drawn more attention due to their excellent stability, although their efficiencies are still lower than those of 3D ones. Here we applied post-treatment of 2D perovskite GAMA5Pb5I16 (GA = guanidinium, MA = methylammonium) films with acetaminophen (AMP) to improve their performance. The efficiency of the solar cells with 2 mg/mL AMP post-treatment increased to 18.01% from 16.72% for those without post-treatment. The efficiency improvement results from the enlarged grain size, reduced trap state density, and better energy level matching after AMP post-treatment. In addition, the stability of the solar cells is improved. The solar cells with AMP post-treatment maintain 91% of the original power conversion efficiency value after aging for 30 days in the atmosphere. This work opens a new approach for the efficiency and stability enhancement of quasi-2D PSCs.

Single-crystalline hole-transporting layers for efficient and stable organic light-emitting devices.

Efficient charge-carrier injection and transport in organic light-emitting devices (OLEDs) are essential to simultaneously achieving their high efficiency and long-term stability. However, the charge-transporting layers (CTLs) deposited by various vapor or solution processes are usually in amorphous forms, and their low charge-carrier mobilities, defect-induced high trap densities and inhomogeneous thickness with rough surface morphologies have been obstacles towards high-performance devices. Here, organic single-crystalline (SC) films were employed as the hole-transporting layers (HTLs) instead of the conventional amorphous films to fabricate highly efficient and stable OLEDs. The high-mobility and ultrasmooth morphology of the SC-HTLs facilitate superior interfacial characteristics of both HTL/electrode and HTL/emissive layer interfaces, resulting in a high Haacke's figure of merit (FoM) of the ultrathin top electrode and low series-resistance joule-heat loss ratio of the SC-OLEDs. Moreover, the thick and compact SC-HTL can function as a barrier layer against moisture and oxygen permeation. As a result, the SC-OLEDs show much improved efficiency and stability compared to the OLEDs based on amorphous or polycrystalline HTLs, suggesting a new strategy to developing advanced OLEDs with high efficiency and high stability.

Femtosecond Laser Ablation of Quantum Dot Films toward Physical Unclonable Multilevel Fluorescent Anticounterfeiting Labels.

Femtosecond laser ablation (FsLA) technology has been demonstrated to achieve programmable ablation and removal of diverse materials with high precision. Owing to the cross-scale and digital processing characteristics, the FsLA technology has attracted increasing interest. However, the moderate repeatability of FsLA limits its application in the fabrication of advanced micro-/nanostructures due to the nonidentity of each laser pulse and fluctuation of environment. Fortunately, moderate repeatability combined with programmable ablation and high precision perfectly matches with the technical requirements of a physical unclonable fluorescent anticounterfeiting label. Herein, we applied FsLA to quantum dot (QD) films to fabricate a physical unclonable multilevel fluorescent anticounterfeiting label. Visual Jilin University logos, quick response (QR) codes, microlines, and microholes have been achieved for the multilevel anticounterfeiting functions. Of particular significance, the microholes with a macroidentical and microidentifiable geometry guarantee the physical unclonable functions (PUFs). Moreover, the fluorescent anticounterfeiting label is compatible with deep learning algorithms that facilitate authentication to be convenient and accurate. This work shows a fantastic future potential to be a core anticounterfeiting technique for commercial products and drugs.