Improvements to perovskite solar cells (PSCs) have focused on increasing their power conversion efficiency (PCE) and operational stability and maintaining high performance upon scale-up to module sizes. We report that replacing the commonly used mesoporous–titanium dioxide electron transport layer (ETL) with a thin layer of polyacrylic acid–stabilized tin(IV) oxide quantum dots (paa-QD-SnO2) on the compact–titanium dioxide enhanced light capture and largely suppressed nonradiative recombination at the ETL–perovskite interface. The use of paa-QD-SnO2 as electron-selective contact enabled PSCs (0.08 square centimeters) with a PCE of 25.7% (certified 25.4%) and high operational stability and facilitated the scale-up of the PSCs to larger areas. PCEs of 23.3, 21.7, and 20.6% were achieved for PSCs with active areas of 1, 20, and 64 square centimeters, respectively. Description Tailoring tin oxide layers Mesoporous titanium dioxide is commonly used as the electron transport layer in perovskite solar cells, but electron transport layers based on tin(IV) oxide quantum dots could be more efficient, with a better-aligned conduction band and a higher carrier mobility. Kim et al. show that such quantum dots could conformally coat a textured fluorine-doped tin oxide electrode when stabilized with polyacrylic acid. Improved light trapping and reduced nonradiative recombination resulted in a certified power conversion efficiency of 25.4% and high operational stability. In larger-area minimodules, active areas as high as 64 square centimeters maintained certified power conversion efficiencies of more than 20%. —PDS Polymer-stabilized tin oxide nanoparticles suppress recombination at the electron-transport layer–perovskite interface.

Conformal quantum dot–SnO2 layers as electron transporters for efficient perovskite solar cells

Photoluminescence blinking—random switching between states of high (ON) and low (OFF) emissivities—is a universal property of molecular emitters found in dyes, polymers, biological molecules and artificial nanostructures such as nanocrystal quantum dots, carbon nanotubes and nanowires. For the past 15 years, colloidal nanocrystals have been used as a model system to study this phenomenon. The occurrence of OFF periods in nanocrystal emission has been commonly attributed to the presence of an additional charge, which leads to photoluminescence quenching by non-radiative recombination (the Auger mechanism). However, this ‘charging’ model was recently challenged in several reports. Here we report time-resolved photoluminescence studies of individual nanocrystal quantum dots performed while electrochemically controlling the degree of their charging, with the goal of clarifying the role of charging in blinking. We find that two distinct types of blinking are possible: conventional (A-type) blinking due to charging and discharging of the nanocrystal core, in which lower photoluminescence intensities correlate with shorter photoluminescence lifetimes; and a second sort (B-type), in which large changes in the emission intensity are not accompanied by significant changes in emission dynamics. We attribute B-type blinking to charge fluctuations in the electron-accepting surface sites. When unoccupied, these sites intercept ‘hot’ electrons before they relax into emitting core states. Both blinking mechanisms can be electrochemically controlled and completely suppressed by application of an appropriate potential.

https://absimage.aps.org/image/MAR12/MWS_MAR12-2011-002227.pdf

Two types of luminescence blinking revealed by spectroelectrochemistry of single quantum dots

Since the report in 2012 of a solid-state perovskite solar cell (PSC) with a power-conversion efficiency (PCE) of 9.7% and a stability of 500 h, intensive efforts have been made to increase the certified PCE, reaching 25.2% in 2019. The PCE of PSCs now exceeds that of conventional thin-film solar-cell technologies, and the rate at which this increase has been achieved is unprecedented in the history of photovoltaics. Moreover, the development of moisture-stable and heat-stable materials has increased the stability of PSCs. Small-area devices ( 100 cm2) substrates required for commercialization. Thus, materials and methods need to be developed for coating large-area PSCs. In this Review, we discuss solution-based and vapour-phase coating methods for the fabrication of large-area perovskite films, examine the progress in performance and the parameters affecting the properties of large-area coatings, and provide an overview of the methodologies for achieving high-efficiency perovskite solar modules. The scalable fabrication of perovskite solar cells and solar modules requires the development of new materials and coating methods. In this Review, we discuss solution-based and vapour-phase coating methods for large-area perovskite films and examine the progress in performance and the parameters affecting large-area coatings.

Scalable fabrication and coating methods for perovskite solar cells and solar modules

Recent Progresses on Defect Passivation toward Efficient Perovskite Solar Cells

Current-density-voltage (J-V) hysteresis in perovskite solar cells (PSCs) is a critical issue because it is related to power conversion efficiency and stability. Although parameters affecting the hysteresis have been already reported and reviewed, little investigation is reported on scan-direction-dependent J-V curves depending on perovskite composition. This review investigates J-V hysteric behaviors depending on perovskite composition in normal mesoscopic and planar structure. In addition, methodologies toward hysteresis-free PSCs are proposed. There is a specific trend in hysteresis in terms of J-V curve shape depending on composition. Ion migration combined with nonradiative recombination near interfaces plays a critical role in generating hysteresis. Interfacial engineering is found to be an effective method to reduce the hysteresis; however, bulk defect engineering is the most promising method to remove the hysteresis. Among the studied methods, KI doping is proved to be a universal approach toward hysteresis-free PSCs regardless of perovskite composition. It is proposed from the current studies that engineering of perovskite film near the electron transporting layer (ETL) and the hole transporting layer (HTL) is of vital importance for achieving hysteresis-free PSCs and extremely high efficiency.

On the Current-Voltage Hysteresis in Perovskite Solar Cells: Dependence on Perovskite Composition and Methods to Remove Hysteresis

Background CC chemokine receptor 9 (CCR9), an organ-specific chemokine receptor, interacts with its exclusive ligand CCL25 to promote tumor proliferation and metastasis. However, the effect of CCR9 on salivary adenoid cystic carcinoma (SACC) malignant behavior remains unknown. This study aimed to investigate the specific molecular mechanism by which CCR9/CCL25 modulates malignant progression in SACC. Methods Immunohistochemistry staining and RT–qPCR analyses were performed to detect the correlation of CCR9 expression and tumor progression-associated markers in SACC. In vitro, SACC cell proliferation and apoptosis were evaluated using Cell Counting Kit-8 and colon formation, and cell migration and invasion were detected by wound healing and transwell assays. Vercirnon was used as an inhibitor of CCR9, and LY294002 was used as an inhibitor of the PI3K/AKT pathway in this study. Western blot and RT–qPCR assays were carried out to measure the downstream factors of the interaction of CCL25 and CCR9. The effect of CCL25 on the development of SACC in vivo was examined by a xenograft tumor model in nude mice following CCL25, Vercirnon and LY294002 treatment. Results CCR9 was highly expressed in SACC compared with adjacent salivary gland tissues, and its level was associated with tumor proliferation and metastases. CCL25 enhanced cell proliferation, migration, and invasion through its interaction with CCR9 and exerted an antiapoptotic effect on SACC cells. Targeting CCR9 via Vercirnon significantly reduced the phosphorylation level of AKT induced by CCL25. CCL25/CCR9 could activate its downstream factors through the PI3K/AKT signaling pathway, such as cyclin D1, BCL2 and SLUG, thus promoting SACC cell proliferation, antiapoptosis, invasion and metastasis. The in vivo data from the xenograft mouse models further proved that CCL25 administration promoted malignant tumor progression by activating the PI3K/AKT pathway. Conclusion The interaction of CCL25 and CCR9 promotes tumor growth and metastasis in SACC by activating the PI3K/AKT signaling pathway, offering a promising strategy for SACC treatment.

CCL25/CCR9 interaction promotes the malignant behavior of salivary adenoid cystic carcinoma via the PI3K/AKT signaling pathway


 Super long perovskite microwires (PMWs) are in a great demand in many fields such as low-loss microcables and integrated optical waveguide. Despite decades of research into PMWs, single crystal PMWs with several centimeters long have not been obtained. Here, ultralong (up to 7.6 centimeters) monoclinic crystal structure CH3NH3PbI3·DMF PMWs have been synthesized. The high-quality microwire exhibits long carrier lifetime of 1775.7 ns. The as-prepared free-standing PMWs can be integrated to any arbitrary substrate and 808 nm near-infrared photodetectors have been successfully demonstrated. The fabricated device shows a high light on/off ratio of 1.79×106 and an extremely low dark current of 2.5 fA at 1 V bias. This work provides a strategy for the solution growth of ultralong microwires.

/pdf/ultralong-free-standing-single-crystal-perovskite-microwires-3y90lt4fqi.pdf

Ultralong free-standing single crystal perovskite microwires with extremely low dark current

The diagnosis and disease management of chronic hepatitis B (CHB) remain challenging due to the elusive assessment of disease severity. Recently, soluble receptor for advanced glycation end-products (sRAGE) has been implicated in the inflammatory-immune response initiated by liver injury. Nonetheless, its natural behavior and clinical importance in CHB remain elusive. One hundred and twenty CHB patients and forty healthy controls (HCs) were enrolled, and the serum sRAGE as well as RAGE expression in biopsy specimens from these subjects was analyzed, and correlation of sRAGE with clinical features as well as its potential predictive value for monitoring the CHB was also evaluated. Reduced serum sRAGE levels and decreased tissular RAGE expression were observed in CHB patients. sRAGE and RAGE were inversely correlated with gradually increased grades of hepatic necroinflammation as well as the routine indicator ALT. Furthermore, receiver operating characteristic (ROC) analysis showed that combination of ALT and sRAGE exerted better predictive power (area under the ROC curve (AUC) of 0.86) for hepatic necroinflammation than that of ALT (AUC of 0.82), sRAGE (AUC of 0.81), or sRAGE-to-ALT ratio (sRAGE/ALT) (AUC of 0.85) alone. More importantly, circulating sRAGE alone exerted valuable predictive power for hepatic moderate-to-severe necroinflammation in CHB patients but with normal ALT (AUC of 0.81) or minimally elevated ALT (AUC of 0.85). In conclusion, reduced serum sRAGE levels may imply an increased severity for necroinflammation, and it may serve as a potential alternative biomarker for monitoring hepatic necroinflammation in CHB. 

/pdf/reduced-circulating-soluble-receptor-for-advanced-glycation-2b8yj6mm.pdf

Reduced Circulating Soluble Receptor for Advanced Glycation End-products in Chronic Hepatitis B Are Associated with Hepatic Necroinflammation

Purpose The objective of this study was to sort out innovative molecular subtypes associated with mitochondrial ribosomal proteins (MRPs) to predict clinical therapy response and determine the presence of circulating markers in hepatocellular carcinoma (HCC) patients. Methods Using an unsupervised clustering method, we categorized the relative molecular subtypes of MRPs in HCC patients. The prognosis, biological properties, immune checkpoint inhibitor and chemotherapy response of the patients were clarified. A signature and nomogram were developed to evaluate the prognosis. Enzyme-linked immunosorbent assay (ELISA) measured serum mitochondrial ribosomal protein L9 (MRPL9) levels in liver disease patients and normal individuals. Receiver operating characteristic (ROC) curves were conducted to calculate the diagnostic effect. The Cell Counting Kit 8 was carried out to examine cell proliferation, and flow cytometry was used to investigate the cell cycle. Transwell assay was applied to investigate the potential of cell migration and invasion. Western blot detected corresponding changes of biological markers. Results Participants were classified into two subtypes according to MRPs expression levels, which were characterized by different prognoses, biological features, and marked differences in response to chemotherapy and immune checkpoint inhibitors. Serum MRPL9 was significantly higher in HCC patients than in normal individuals and the benign liver disease group. ROC curve analysis showed that MRPL9 was superior to AFP and Ferritin in differentiating HCC from healthy and benign patients, or alone. Overexpressed MRPL9 could enhance aggressiveness and facilitate the G1/S progression in HCC cells. Conclusion We constructed novel molecular subtypes based on MRPs expression in HCC patients, which provided valuable strategies for the prediction of prognosis and clinical personalized treatment. MRPL9 might act as a reliable circulating diagnostic biomarker and therapeutic target for HCC patients.

Classification of the mitochondrial ribosomal protein-associated molecular subtypes and identified a serological diagnostic biomarker in hepatocellular carcinoma

Weijian Chen

Papers

CCL25/CCR9 interaction promotes the malignant behavior of salivary adenoid cystic carcinoma via the PI3K/AKT signaling pathway

Ultralong free-standing single crystal perovskite microwires with extremely low dark current

Reduced Circulating Soluble Receptor for Advanced Glycation End-products in Chronic Hepatitis B Are Associated with Hepatic Necroinflammation

Classification of the mitochondrial ribosomal protein-associated molecular subtypes and identified a serological diagnostic biomarker in hepatocellular carcinoma

Alpha-cyano-4-hydroxycinnamic acid alleviates renal fibrosis and inflammation in chronic kidney disease