The Narrow Synthetic Window for Highly Homogenous InP Quantum Dots toward Narrow Red Emission.

Low-toxicity InP-based quantum dots (QDs) exhibit potential for replacing Cd/Pb-containing QDs in the visible and near-infrared regions. Despite advancements, further improvement relies on synthesizing homogeneous InP QDs to achieve a high color purity. In a commonly employed two-step "seed-mediated" synthetic approach, we demonstrate the high sensitivity of InP seed sizes and size distribution to the quantities of trioctylphosphine (TOP) and tris(trimethylsilyl)phosphine [(TMS)3P], attributed to the process of "self-focusing of size distribution" and enhanced reactivity of In-oleate through coordination with TOP. During growth, the processes of size focusing and defocusing are modulated by the accumulation of oleic acid and TOP molecules, as well as the amount of (TMS)3P in the growth precursor, which may relate to the dissolution process of InP magic size clusters. Through precise control, the best valley/depth ratio of InP QDs was 0.52 at the first absorption peak at 571 nm, resulting in luminescence with a full width at half-maximum of 35 at 620 nm with an absolute photoluminescence quantum yield around 90% after heteroepitaxial growth with ZnSe and ZnS shells.

Near-Infrared LEDs Based on Quantum Cutting-Activated Electroluminescence of Ytterbium Ions.

Cesium lead halide perovskite nanocrystals (PNCs) exhibit promising prospects for application in optoelectronic devices. However, electroactivated near-infrared (NIR) PNC light-emitting diodes (LEDs) with emission peaks over 800 nm have not been achieved. Herein, we demonstrate the electroactivated NIR PNC LEDs based on Yb3+-doped CsPb(Cl1-xBrx)3 PNCs with extraordinary high NIR photoluminescence quantum yields over 170%. The fabricated NIR LEDs possess an irradiance of 584.7 µW cm-2, an EQE of 1.2%, and a turn-on voltage of 3.1 V. The ultrafast quantum cutting process from the PNC host to Yb3+ has been revealed as the main mechanism of electroluminescence (EL)-activated Yb3+ for the first time via exploring how the trend between the EL intensity of PNC and Yb3+ varies with different voltages along with the tendency of temperature- and doping-concentration-dependent PL and EL spectra. This work will extend the application of PNCs to optical communication, night-vision devices, and biomedical imaging.

Locally secreted BiTEs complement CAR T cells by enhancing killing of antigen heterogeneous solid tumors.

Bispecific T cell engagers (BiTEs) are bispecific antibodies that redirect T cells to target antigen-expressing tumors. We hypothesized that BiTE-secreting T cells could be a valuable therapy in solid tumors, with distinct properties in mono- or multi-valent strategies incorporating chimeric antigen receptor (CAR) T cells. Glioblastomas represent a good model for solid tumor heterogeneity, representing a significant therapeutic challenge. We detected expression of tumor-associated epidermal growth factor receptor (EGFR), EGFR variant III, and interleukin-13 receptor alpha 2 (IL13Rα2) on glioma tissues and cancer stem cells. These antigens formed the basis of a multivalent approach, using a conformation-specific tumor-related EGFR targeting antibody (806) and Hu08, an IL13Rα2-targeting antibody, as the single chain variable fragments to generate new BiTE molecules. Compared with CAR T cells, BiTE T cells demonstrated prominent activation, cytokine production, and cytotoxicity in response to target-positive gliomas. Superior response activity was also demonstrated in BiTE-secreting bivalent T cells compared with bivalent CAR T cells in a glioma mouse model at early phase, but not in the long term. In summary, BiTEs secreted by mono- or multi-valent T cells have potent anti-tumor activity in vitro and in vivo with significant sensitivity and specificity, demonstrating a promising strategy in solid tumor therapy.

Upregulation of miR-184 and miR-19a-3p induces endothelial dysfunction by targeting AGO2 in Kawasaki disease.

BACKGROUND: Endothelial dysfunction is a marked feature of Kawasaki disease during convalescence, but its pathogenesis is currently unclear. Circulating microRNAs (miRNAs) are associated with the progression of Kawasaki disease. However, the role and mechanism of circulating miRNAs in endothelial dysfunction are largely unknown. Kawasaki disease patients were found to have a unique circulating miRNA profile, including upregulation of miRNA-210-3p, miR-184 and miR-19a-3p, compared to non-Kawasaki disease febrile controls. This study aimed to investigate the effects of these three miRNAs on endothelial function. METHODS: Overexpression of miRNAs in human umbilical vein endothelial cells was done by transfection of miRNA mimics. The tube formation assay was used to evaluate the function of human umbilical vein endothelial cells. The potential binding sites of miRNAs on 3'untranslated regions were predicted by using TargetScan database and validated by dual luciferase reporter assay. The protein expression of AGO2, PTEN and VEGF in human umbilical vein endothelial cells was detected by Western blot. Overexpression of AGO2 in human umbilical vein endothelial cells was done by transfection of AGO2 expression plasmids. RESULTS: Overexpression of miRNA-184 and miRNA-19a-3p, but not miR-210-3p, impaired the function of human umbilical vein endothelial cells. Mechanistically, miR-184 and miR-19a-3p could target the 3'untranslated regions of AGO2 mRNA to downregulate its expression and subsequently impede the AGO2/PTEN/VEGF axis. To be noted, the rescue of the expression of AGO2 remarkably recovered the function that was impaired by overexpression of miRNA-184 and miRNA-19a-3p. CONCLUSIONS: This study suggested that miR-184 and miR-19a-3p could target AGO2/PTEN/VEGF axis to induce endothelial dysfunction in Kawasaki disease.

Reversible Transformation between Cs3Cu2I5 and CsCu2I3 Perovskite Derivatives and Its Anticounterfeiting Application.

Lead halide perovskites have promising values in photoelectronic and photovoltaic applications, but the toxicity of lead is a hard barrier. Copper halide perovskite derivatives (CHPDs), as a lead-free substitution of lead halide perovskites, also exhibit excellent photoelectric properties. Here, we present a facile one-step route for the synthesis of blue-emissive Cs3Cu2I5 (emission at 440 nm) and yellow-emissive CsCu2I3 (emission at 552 nm) CHPDs in ethanol at room temperature. Triggered by ethanol or CsI, a reversible chemical transformation accompanied by emissive color change between Cs3Cu2I5 and CsCu2I3 CHPDs was achieved. The reversible transformation mechanism was discussed, and this transformation was employed for effective anticounterfeiting.

Room Temperature Synthesis of All Inorganic Lead-Free Zero-Dimensional Cs4SnBr6 and Cs3KSnBr6 Perovskites.

Lead halide perovskites are excellent candidates for photoelectronic and photovoltaic applications, but the toxicity from lead is extremely concerning. Recently, Sn-based zero-dimensional lead-free perovskites synthesized using solid-state reaction techniques have become a new focus in the field. Here, we report a simple room temperature antisolvent method for the synthesis of all inorganic lead-free green emissive Cs4SnBr6 (emission at 524 nm) and cyan emissive Cs3KSnBr6 (emission at 500 nm) zero-dimensional perovskites. Their photoluminescence quantum yields reach 20% and 35%, respectively. In addition, they maintain their emission for 46 and 55 h in the air, respectively, compared to only 5 min of CsSnBr3. This method provides a convenient way to do the research and apply these highly emissive perovskites.

Ivermectin inhibits the growth of glioma cells by inducing cell cycle arrest and apoptosis in vitro and in vivo.

Glioma, the most predominant primary malignant brain tumor, remains uncured due to the absence of effective treatments. Hence, it is imperative to develop successful therapeutic agents. This study aimed to explore the antitumor effects and mechanisms of ivermectin (IVM) in glioma cells in vitro and in vivo. The effects of IVM on cell viability, cell cycle arrest, apoptosis rate, and morphological characteristics were determined respectively by MTT assay/colony formation assay, flow cytometry, and transmission electron microscope. In addition, the expression levels of cycle-related and apoptosis-associated proteins were individually examined by Western blot analysis. Moreover, cell proliferation and apoptosis analyses were carried out by TUNEL, Ki-67, cleaved caspase-3, and cleaved caspase-9 immunostaining assay. Our results demonstrated that IVM has a potential dosage-dependent inhibition effect on the apoptosis rate of glioma cells. Meanwhile, the results also revealed that IVM induced apoptosis by increasing caspase-3 and caspase-9 activity, upregulating the expressions of p53 and Bax, downregulating Bcl-2, activating cleaved caspase-3 and cleaved caspase-9, and blocking cell cycle in G0/G1 phase by downregulating levels of CDK2, CDK4, CDK6, cyclin D1, and cyclin E. These findings suggest that IVM has an inhibition effect on the proliferation of glioma cells by triggering cell cycle arrest and inducing cell apoptosis in vitro and in vivo, and probably represents promising agent for treating glioma.

Oxalic Acid Enabled Emission Enhancement and Continuous Extraction of Chloride from Cesium Lead Chloride/Bromide Perovskite Nanocrystals.

All-inorganic cesium lead halide perovskite nanocrystals (NCs) have demonstrated excellent optical properties and an encouraging potential for optoelectronic applications; however, mixed-halide perovskites, especially CsPb(Cl/Br)3 NCs, still show lower photoluminescence quantum yields (PL QY) than the corresponding single-halide materials. Herein, anhydrous oxalic acid is used to post-treat CsPb(Cl/Br)3 NCs in order to initially remove surface defects and halide vacancies, and thus, to improve their PL QY from 11% to 89% for the emission of 451 nm. Furthermore, due to the continuous chelating reaction with the oxalate ion, chloride anions from the mixed-halide CsPb(Cl/Br)3 perovskite NCs could be extracted, and green emitting CsPbBr3 NCs with PL QY of 85% at 511 nm emission are obtained. Besides being useful to improve the emission of CsPb(Cl/Br)3 NCs, the oxalic acid treatment strategy introduced here provides a further tool to adjust the distribution of halide anions in mixed-halide perovskites without using any halide additives.

Water-Assisted Size and Shape Control of CsPbBr3 Perovskite Nanocrystals.

Lead-halide perovskites are well known to decompose rapidly when exposed to polar solvents, such as water. Contrary to this common-place observation, we have found that through introducing a suitable minor amount of water into the reaction mixture, we can synthesize stable CsPbBr3 nanocrystals. The size and the crystallinity, and as a result the band gap tunability of the strongly emitting CsPbBr3 nanocrystals correlate with the water content. Suitable amounts of water change the crystallization environment, inducing the formation of differently shaped perovskites, namely spherical NCs, rectangular nanoplatelets, or nanowires. Bright CsPbBr3 nanocrystals with the photoluminescence quantum yield reaching 90 % were employed for fabrication of inverted hybrid inorganic/organic light-emitting devices, with the peak luminance of 4428 cd m-2 and external quantum yield of 1.7 %.

TUSC3 suppresses glioblastoma development by inhibiting Akt signaling.

Glioblastoma multiform is one of the most common and most aggressive brain tumors in humans. The molecular and cellular mechanisms responsible for the onset and progression of GBM are elusive and controversial. The function of tumor suppressor candidate 3 (TUSC3) has not been previously characterized in GBM. TUSC3 was originally identified as part of an enzyme complex involved in N-glycosylation of proteins, but was recently implicated as a potential tumor suppressor gene in a variety of cancer types. In this study, we demonstrated that the expression levels of TUSC3 were downregulated in both GBM tissues and cells, and also found that overexpression of TUSC3 inhibits GBM cell proliferation and invasion. In addition, the effects of increased levels of methylation on the TUSC3 promoter were responsible for decreased expression of TUSC3 in GBM. Finally, we determined that TUSC3 regulates proliferation and invasion of GBM cells by inhibiting the activity of the Akt signaling pathway.

Risk Factors for Infections Related to Lumbar Drainage in Spontaneous Subarachnoid Hemorrhage.

BACKGROUND: A solid knowledge associated with lumbar drainage (LD)-related infections in spontaneous subarachnoid hemorrhage (SAH) patients is necessary and that would be useful in taking effective measures to cope with this complication. We aimed to describe incidence rates and risk factors associated with LD-related infections in SAH patients. METHODS: A retrospective review was performed on SAH patients who underwent LD between July 2010 and August 2015. Patient charts were reviewed to retrieve demographic, clinical, and laboratory data. LD-related infections were defined based on culture results of cerebrospinal fluid in combination with clinical symptoms. Infection rates were calculated, and a logistic regression model was developed to identify risk factors. RESULTS: A total of 629 SAH patients (25-82 years age range, 42.8 % male) were treated with LD in the period. LD-related infections were identified in 36 patients (5.7 %). Longer duration of LD (≥4 days: p = 0.0037) and puncture site leakage (p < 0.0001) appeared to be risk factors for infection. The infection rate increased with length of the hospital stay (16-20 days: p = 0.0032; ≥21 days: p = 0.0007). 84.6 % of the isolated bacteria were Gram-positive, and the most commonly associated pathogens were Methicillin-resistant coagulase-negative Staphylococcus (MRCNS, 61.5 %). CONCLUSIONS: The patients with LD for more than 4 days or with puncture site leakage had more risk of infection. Infected patients were more likely to stay longer in the hospital. MRCNS were identified as the most frequent causal pathogens. And the use of antibiotics during LD did not appear to reduce the risk of infection.

Human amniotic epithelial stem cells inhibit microglia activation through downregulation of tumor necrosis factor-α, interleukin-1ß and matrix metalloproteinase-12 in vitro and in a rat model of intracerebral hemorrhage.

BACKGROUND AIMS: The molecular mechanisms by which stem cell transplantation improves functional recovery after intracerebral hemorrhage (ICH) are not well understood. Accumulating evidence suggests that microglia cells are activated shortly after ICH and that this activation contributes to secondary ICH-induced brain injury. We studied the effect of human amniotic epithelial stem cells (HAESCs) on microglia activation. METHODS: To study the effect of HAESCs in vitro, we used thrombin to activate the microglia cells. Twenty-four hours after thrombin treatment, the levels of tumor necrosis factor-α and interleukin-1ß were measured by enzyme-linked immunosorbent assay. In vivo, the HAESCs were transplanted into the rat striatum 1 day after collagenase-induced ICH. The expression levels of matrix metalloproteinase (MMP)-12 and microglia infiltration in the peri-hematoma tissues were determined 7 days after ICH through the use of reverse transcriptase-polymerase chain reaction and immunohistochemical analysis, respectively. RESULTS: Thrombin-activated microglia expression of tumor necrosis factor-α, interleukin-1ß and MMP-12 was significantly reduced through contact-dependent and paracrine mechanisms when the HAESCs were co-cultured with microglia cells. After transplantation of HAESCs in rat brains, the expression levels of MMP-12 and microglia infiltration in the peri-hematoma tissues were significantly reduced. CONCLUSIONS: Our observations suggest that microglia activation could be inhibited by HAESCs both in vitro and in vivo, which may be an important mechanism by which the transplantation of HAESCs reduces brain edema and ameliorates the neurologic deficits after ICH. Therefore, we hypothesize that methods for suppressing the activation of microglia and reducing the inflammatory response can be used for designing effective treatment strategies for ICH.

Risk Factors for Seizures After Titanium Cranioplasty: Five-Year Experience from a Single Institution.

OBJECTIVE: Seizures are one of the complications that can occur after cranioplasty (CP). In some regions, titanium mesh remains the material of choice for CP. However, risk factors for seizures after titanium CP have been less studied. The purpose of this study was to identify potential risk factors for early seizures (≤7 days) and late seizures (>8 days) after titanium CP in a single institution. METHODS: A retrospective review was conducted of 241 consecutive patients who received titanium CP at the First Affiliated Hospital of Harbin Medical University from January 2016 to December 2020. Univariate and multivariable logistic regression analyses were performed to determine the independent risk factors for new-onset seizures after titanium CP. RESULTS: Fifteen patients (6.22%) experienced early post-CP seizures, and late post-CP seizures were observed in 81 patients (33.61%). A flaccid concave cranial defect (P = 0.042) was associated with early post-CP seizures, whereas hypertension (P < 0.001) was the only significant predictor for late seizures after titanium CP. CONCLUSIONS: Seizure is a common complication after titanium CP, especially in patients who do not receive prophylactic antiepileptic drugs before the procedure. Risk factors for new-onset seizures at different periods after titanium CP were found to be different. In addition, radiologic factors before titanium CP may play a role in early new-onset seizures after titanium CP and should not be ignored.

Exploring the causal association between genetically determined circulating metabolome and hemorrhagic stroke.

Background: Hemorrhagic stroke (HS), a leading cause of death and disability worldwide, has not been clarified in terms of the underlying biomolecular mechanisms of its development. Circulating metabolites have been closely associated with HS in recent years. Therefore, we explored the causal association between circulating metabolomes and HS using Mendelian randomization (MR) analysis and identified the molecular mechanisms of effects. Methods: We assessed the causal relationship between circulating serum metabolites (CSMs) and HS using a bidirectional two-sample MR method supplemented with five ways: weighted median, MR Egger, simple mode, weighted mode, and MR-PRESSO. The Cochran Q-test, MR-Egger intercept test, and MR-PRESSO served for the sensitivity analyses. The Steiger test and reverse MR were used to estimate reverse causality. Metabolic pathway analyses were performed using MetaboAnalyst 5.0, and genetic effects were assessed by linkage disequilibrium score regression. Significant metabolites were further synthesized using meta-analysis, and we used multivariate MR to correct for common confounders. Results: We finally recognized four metabolites, biliverdin (OR 0.62, 95% CI 0.40-0.96, PMVMR = 0.030), linoleate (18. 2n6) (OR 0.20, 95% CI 0.08-0.54, PMVMR = 0.001),1-eicosadienoylglycerophosphocholine* (OR 2.21, 95% CI 1.02-4.76, PMVMR = 0.044),7-alpha-hydroxy-3 -oxo-4-cholestenoate (7-Hoca) (OR 0.27, 95% CI 0.09-0.77, PMVMR = 0.015) with significant causal relation to HS. Conclusion: We demonstrated significant causal associations between circulating serum metabolites and hemorrhagic stroke. Monitoring, diagnosis, and treatment of hemorrhagic stroke by serum metabolites might be a valuable approach.

OPN gene polymorphism and the serum OPN levels confer the susceptibility and prognosis of ischemic stroke in Chinese patients.

AIM: To investigate the association of Osteopontin (OPN) gene polymorphism and serum thrombin-cleaved OPN level with the susceptibility to ischemic stroke (IS) and its prognosis. METHODS: A total of 377 patients with IS and 551 healthy individuals were recruited. The OPN gene polymorphisms at -156 G>GG, -443 C>T and -66 T>G were genotyped. Serum full-length and the thrombin-cleaved OPN were determined. RESULTS: We found that only the -443 C>T polymorphism was significantly associated with the susceptibility to IS. The -443 CC represented a near 2 time higher risk for IS incidence than TT carriers. Also, the -443 CC genotype had significantly poorer outcome and they significantly had higher occurrence for bad recovery as determined by modified Rankin Scale (mRS) (OR=2.18, p=0.043) and Barthel Index (BI) (OR=2.12, p=0.05). The mean serum thrombin-cleaved OPN level in IS group were significantly higher than that in control group. ROC analysis showed that the thrombin-cleaved OPN level (cut-off value, 166.8 ng/ml) can discriminate IS patients from controls with a specificity of 86.3% and a sensitivity of 57.7%. The serum thrombin-cleaved OPN was significantly associated with the clinical outcome at 12 months after discharge from hospital. CONCLUSION: These results suggest that the -443 C>T polymorphism of OPN gene and serum thrombin-cleaved OPN can be used as a biomarker for the susceptibility and prognosis of IS patients.

The MAI score: A novel score to early predict shunt-dependent hydrocephalus in patients with aneurysmal subarachnoid hemorrhage after surgery.

OBJECTIVE: As a chronic complication of aneurysmal subarachnoid hemorrhage(aSAH), Shunt dependent hydrocephalus (SDHC) often leads to severe neurological deficits. At present, risk factors of SDHC after aSAH are being refined. So this study aims to investigate independent risk factors and develop a novel score to identify early the patients who require a permanent shunt. METHOD: Five hundred twenty-four patients treated in the first affiliated hospital of Harbin medical university from March 2019 to March 2021 were analyzed. We collected clinical and radiographic data of patients within 72 h after the ictus. The relevant factors were firstly analyzed by univariate analysis, and the significant factors (p < 0.05) were included in the multivariate logistic regression analysis to obtain the independent risk factors with statistical differences. The MAI score was established based on the contribution of different independent risk factors to the outcome. the new score was validated in another cohort (97 patients with aSAH from April and June 2021). RESULT: We enrolled 524 aneurysm patients and 41(7.82%) patients who underwent ventriculoperitoneal shunt (VPS) after aneurysm treatment. Based on univariate and multivariate analysis, Acute Hydrocephalus (OR 6.498,:95% confidence interval (CI) 1.98-21.33, p = 0.002), Intraventricular hemorrhage (OR 3.55,:95%CI 1.189-10.599, p = 0.023) and Modified Fisher score ≥ 3 (OR 5.846, 95%CI 2.649-12.900, p = 0.001) were independent risk factors. The novel score was assigned according to the contribution of different independent risk factors to the results. The MAI score: Modified Fisher grade ≥ 3 (1 point), Acute Hydrocephalus (1 point), Intraventricular hemorrhage (1 point). In the receiver operating characteristic curve analysis, the area under the curve (AUC) for the MAI score is 0.773 (p < 0.0001, 95%CI 0.686-0.861). Patients scoring 2-3 MAI points showed a 10-fold higher risk for shunt dependency than patients scoring 0-1 MAI points (p < 0.001). We performed internal validation of the MAI scoring system. The scoring system reliably predicted SDHC after aSAH. The AUC of the internal validation was 0.950 (p ＝ 0.002, 95%CI 0.863-1.000). CONCLUSION: We develop a novel score based on univariate and multivariate analysis. The effectiveness of the MAI score has been confirmed in this study, which can more accurately predict SDHC after aASH and can be widely used in clinical practice. Prospective studies are needed for validation in the future.

Safety Analysis of Simultaneous Cranioplasty and Ventriculoperitoneal Shunt Placement.

AIM: To investigate the safety of combined cranioplasty (CP) and ventriculoperitoneal shunt (VPS) placement. Furthermore, we investigated whether the sequence of these procedures affects the postoperative complication rates associated with staged CP and VPS placement. MATERIAL AND METHODS: We retrospectively investigated patients who developed communicating hydrocephalus after decompressive craniectomy and subsequently underwent VPS placement and CP at the hospital at which this study was performed between January 2009 and December 2019. Patients were categorized into group 1 (simultaneous CP and VPS placement) and group 2 (CP and VPS placement performed separately). Group 2 was subcategorized into subgroup 2a (CP performed before VPS placement) and subgroup 2b (VPS placement performed before CP). The Student?s t and Chi square tests were used to analyze intergroup differences. RESULTS: This study included 86 patients; 22 in group 1 and 64 in group 2 (24 patients in subgroup 2a and 40 patients in subgroup 2b). No statistically significant difference was observed in the overall complication rates between groups 1 and 2 (36.4% vs. 28.1%, P=0.591). However, the incidence of infections was significantly higher in group 1 than in group 2 (22.7% vs. 4.7%, P=0.024). Subgroup analysis showed that the overall complication rate was signi?cantly lower in subgroup 2a than in subgroup 2b (12.5% vs. 37.5%, P=0.031). CONCLUSION: Simultaneous CP and VPS placement is associated with a high incidence of infections. Moreover, compared with initial CP, initial VPS placement is associated with a significantly higher risk of overall complications in patients who undergo a staged procedure.

Hematoma volume affects the accuracy of computed tomographic angiography 'spot sign' in predicting hematoma expansion after acute intracerebral hemorrhage.

BACKGROUND: We hypothesized that the presence of tiny, enhancing foci ('spot sign') within acute hematomas is associated with hematoma expansion. METHODS: We retrospectively analyzed the effect of hematoma volume on accuracy of computed tomographic angiography (CTA) in predicting hematoma expansion in 312 patients with acute intracerebral hemorrhage (ICH). The patients were divided into 2 groups according to their initial hematoma volume (<30 vs. ≥30 ml). CTA was performed at admission and 24 h after initial presentation. RESULTS: The <30-ml group consisted of 203 patients of whom 42 had hematoma expansion (20.9%). The ≥30-ml group consisted of 109 patients of whom 34 had hematoma expansion (31.19%). In the <30-ml group, the sensitivity and specificity of CTA in predicting hematoma expansion were 71.4 and 93.8%, respectively. In the ≥30-ml group, the sensitivity and specificity of CTA were 85.7 and 91.9%, respectively. For all 312 patients, the area under the curve was 0.86 (p < 0.001, 95% CI 0.80-0.92); the sensitivity and specificity of CTA were 77.9 and 93.2%, respectively. CONCLUSIONS: CTA can reliably predict hematoma expansion in clinical practice, especially for hematomas >30 ml.

Lead-Free Halide Perovskites for Light Emission: Recent Advances and Perspectives.

Lead-based halide perovskites have received great attention in light-emitting applications due to their excellent properties, including high photoluminescence quantum yield (PLQY), tunable emission wavelength, and facile solution preparation. In spite of excellent characteristics, the presence of toxic element lead directly obstructs their further commercial development. Hence, exploiting lead-free halide perovskite materials with superior properties is urgent and necessary. In this review, the deep-seated reasons that benefit light emission for halide perovskites, which help to develop lead-free halide perovskites with excellent performance, are first emphasized. Recent advances in lead-free halide perovskite materials (single crystals, thin films, and nanocrystals with different dimensionalities) from synthesis, crystal structures, optical and optoelectronic properties to applications are then systematically summarized. In particular, phosphor-converted LEDs and electroluminescent LEDs using lead-free halide perovskites are fully examined. Ultimately, based on current development of lead-free halide perovskites, the future directions of lead-free halide perovskites in terms of materials and light-emitting devices are discussed.

Charge transfer between lead halide perovskite nanocrystals and single-walled carbon nanotubes.

A charge transfer study between lead halide-based perovskite nanocrystals and single-walled carbon nanotubes (PNC@CNT nanocomposite) was performed. Solution-processed MAPbX3 PNCs displayed very bright luminescence, but it quenched in the presence of CNTs. This was attributed to the electron transfer from PNCs to CNTs. The detailed changes in fluorescence lifetime were investigated through time-correlated single-photon counting (TCSPC), which suggested mixed static and dynamic quenching along with a decrease in the lifetime. Morphological changes were investigated via transmission electron microscopy (TEM) and attributed to the incorporation of PNCs on long CNTs. Also, the PNC@CNT nanocomposite was explored for photoinduced current response, which indicated an ∼3 fold increase in photoconductivity under light illumination (with a 1 mV bias). This electron transfer study between PNCs and CNTs contributes to the exploration of charge dynamics.