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Alkali metals have been used to obtain high-performance perovskite light-emitting diodes. In this review, we present an overview of the advances in alkali metal ions applied in PeLEDs. Challenges and the outlook are presented for their future applications.

The antioxidant capacity of acidic media and its effect on the efficiency of perovskite solar cells were investigated. A vertical antioxidant strategy to inhibit the diffusion of Sn4+ in precursor solutions and perovskite films is developed.

Over recent years, the efficiency of tin-based perovskite solar cells (PSCs) has exceeded 14%, which indicates their significant potential in the photovoltaic field.

Solvent engineering is playing an important role in improving the performance of perovskite light-emitting diode (PeLED) devices. In this review, solvent-based strategies for efficient PeLEDs are mainly discussed and an outlook is also proposed.

With the rapid development of the Internet of Things (IoTs), photovoltaics (PVs) has a vast market supply gap of billion dollars. Moreover, it also puts forward new requirements for the development of indoor photovoltaic devices (IPVs). In recent years, PVs represented by organic photovoltaic cells (OPVs), silicon solar cells, dye-sensitized solar cells (DSSCs), etc. considered for use in IoTs mechanisms have also been extensively investigated. However, there are few reports on the indoor applications of perovskite devices, even though it has the advantages of better performance. In fact, perovskite has the advantages of better bandgap adjustability, lower cost, and easier preparation of large-area on flexible substrates, compared with other types of IPVs. This review starts from the development status of IoTs and investigates the cost, technology, and future trends of IPVs. We believe that perovskite photovoltaics is more suitable for indoor applications and review some strategies for fabricating high-performance perovskite indoor photovoltaic devices (IPVs). Finally, we also put forward a perspective for the long-term development of perovskite IPVs., With the rapid development of the Internet of Things (IoTs), photovoltaics (PVs) has a vast market supply gap of billion dollars.

With the efforts of researchers from all over the world, metal halide perovskite solar cells (PSCs) have been booming rapidly in recent years. Generally, perovskite films are sensitive to surrounding conditions and will be changed under the action of physical fields, resulting in lattice distortion, degradation, ion migration, and so on. In this review, the progress of physical fields manipulation in PSCs, including the electric field, magnetic field, light field, stress field, and thermal field are reviewed. On this basis, the influences of these fields on PSCs are summarized and prospected. Finally, challenges and prospective research directions on how to make better use of external-fields while minimizing the unnecessary and disruptive impacts on commercial PSCs with high-efficiency and steady output are proposed.

The generation of photoinduced defects and freely moving halogen ions is dynamically updated in real time. Accordingly, most reported strategies are static and short-term, which make their improvements in photostability very limited. Therefore, seeking new passivation strategies to match the dynamic characteristics of defect generation is very urgent. Without newly generated defects, a passivation molecule should exist in the configuration that would not become the initiation sites for defect generation. With newly generated defects, the passivation molecule should transfer into the other configuration that possesses the passivation sites. Herein, a classical photoisomeric molecule, spiropyran, is adopted, whose pre- and post-isomeric forms meet the requirements for two different configurations, to realize the state transition once the photoinduced defects appear during subsequent operation and dynamic capture for continuous renewal of defects. Consequently, spiropyrans work as light-triggered and self-healing sustainable passivation sites to realize continuous defect repair. The target devices retain 93% and 99% of their initial power conversion efficiencies after 456 h aging under ultraviolet illumination and 1200 h aging under full-spectrum illumination, respectively. This work provides a novel concept of sustainable passivation strategy to realize continuous defect-passivation and film-healing in perovskite photovoltaics.

Defect states play an important role in the photovoltaic performance of metal halide perovskites. Particularly, the passivation of surface defects has made great contributions to high-performance perovskite photovoltaics. This highlights the importance of understanding the surface defects from a fundamental level by developing more accurate and operando characterization techniques. Herein, a strategy to enable the surface carriers and photocurrent distributions on perovskite films to be visualized in the horizontal direction is put forward. The visual image of photocurrent distribution is realized by combining the static local distribution of carriers provided by scanning near-field optical microscopy with the dynamic transporting of carriers achieved via a scanning photocurrent measurement system. Taking a surface passivated molecule as an example, a comprehensive defect scene including static and dynamic as well as local and entire conditions is obtained using this strategy. The comprehensive analysis of the trap states in perovskite films is pioneered vertically and horizontally, which will powerfully promote the deep understanding of defect mechanisms and carrier behavior for the goal of fabricating high-performance perovskite optoelectronic devices.

Compared with highly efficient green, red, and near-infrared perovskite light-emitting diodes (PeLEDs), the performance of blue PeLEDs is still unsatisfactory due to the serious spectral instability issue at high working voltages. In this work, a multidentate amine-based ligand with four amino groups is utilized to achieve spectral stable blue quasi-2D PeLEDs. As a result, the optimized quasi-2D perovskite films exhibit stable photoluminescence spectra under continuous UV illumination and heating. Finally, the blue quasi-2D PeLEDs emitting at 478 nm with the peak external quantum efficiency up to 4.8% are achieved. Meanwhile, there is no obvious peak shift of the electroluminescence spectral under high external working voltages, exhibiting excellent spectral stability. The findings in this work confirm the validity of this strategy, providing a strategy to achieve steady blue PeLEDs.

Perovskite photovoltaics are strong potential candidates to drive low-power off-grid electronics for indoor applications. Compared with rigid devices, flexible perovskite devices can provide a more suitable surface for indoor small electronic devices, enabling them have a broader indoor application prospect. However, the mechanical stability of flexible perovskite photovoltaics is an urgent issue solved. Herein, a kind of 3D crosslinking agent named borax is selected to carry out grain boundary penetration treatment on perovskite film to realize full-dimensional stress release. This strategy improves the mechanical and phase stabilities of perovskite films subjected to external forces or large temperature changes. The fabricated perovskite photovoltaics deliver a champion power conversion efficiency (PCE) of 21.63% under AM 1.5G illumination, which is the highest one to date. The merit of low trap states under weak light makes the devices present a superior indoor PCE of 31.85% under 1062 lux (LED, 2956 K), which is currently the best flexible perovskite indoor photovoltaic device. This work provides a full-dimensional grain boundary stress release strategy for highly stable flexible perovskite indoor photovoltaics.

To study the role and mechanism of microRNA-16 (miR-16) in the proliferation, invasion and apoptosis of ovarian epithelial carcinoma cells in vitro.The SKOV-3 cells were transfected with miR-16 mimics or negative control RNA (NC) by lipofectamine 2000. The expression of miR-16 was detected by real-time reverse transcription (RT)-PCR in SKOV-3 cells, and western blot was used to detect the expression of vascular endothelial growth factor (VEGF), matrix metalloproteinase-2 (MMP-2) and bcl-2 protein. Methyl thiazolyl tetrazolium (MTT), 5-ethynyl-2'-deoxyuridine (EdU) and transwell assay were used to determine the proliferation and invasion abilities. And the rate of apoptotic cell was detected by flow cytometry method.(1) The expression level of miR-16 in the transfection cells group was significantly higher than that in NC group (125.93 ± 15.30 versus 0.78 ± 0.16, P0.01). (2) The relative expression level of VEGF protein in transfection cells, NC and blank control group was 0.58 ± 0.05, 1.22 ± 0.03, 1.20 ± 0.03, MMP-2 protein was 0.63 ± 0.03, 1.16 ± 0.03, 1.21 ± 0.03, and bcl-2 protein 0.52 ± 0.03, 1.19 ± 0.05, 1.28 ± 0.06, respectively. The level of VEGF, MMP-2 and bcl-2 protein in the transfection group were lower than those in other control groups, and there were significantly differences among them (all P0.01). (3) After transfected 4 days, the inhibition rate of cell proliferation in the transfection group was dramatically higher than that in NC group [(37.2 ± 6.2)% versus (3.6 ± 3.2)%, P = 0.001]. (4) The percentage rate of proliferative cells in the transfection, NC and blank control group was (12.3 ± 0.8)%, (23.4 ± 1.8)%, (31.1 ± 4.9)%. And it was lower in the transfection group (P0.05). (5) Decreased cells via the transwell member in the transfection group (6 ± 3) were detected as compared with NC group (40 ± 9) and blank control group (48 ± 8, P0.01). (6) Twenty-four hours after cultured in serum starvation and hypoxia, the rate of the viable and late apoptotic cells in the transfection group were significantly higher than those in NC group and blank control group [the rate of viable apoptotic cell was (16.9 ± 2.1)%, (10.3 ± 1.7)% and (9.0 ± 0.8)% respectively, P0.01; the rate of late apoptotic cell was (13.4 ± 3.3)%, (3.2 ± 1.8)% and (0.7 ± 0.6)% respectively, P0.01]. After cultured 48 hours, total apoptotic cells in the transfection group was significantly more than those in other groups (P0.01).miR-16 might inhibit the proliferation, invasion of ovarian epithelial carcinoma cells and enhance their sensitivity to apoptotic stimuli via downregulation of the expression of VEGF, MMP-2 and bcl-2 protein.

To investigate the role and mechanism of microRNA-21(miR-21) in the proliferation and apoptosis of ovarian epithelial carcinoma cells.A short-hairpin RNA specifically targeting miR-21 plasmid was constructed, and the recombinant was identified by restriction endonuclease analysis and DNA sequencing. Three experimental groups were included, transfection group (transfected with pSIREN-miR-21), negative control group (transfected with pSIREN-miR-21-neg) and blank control group (without transfection plasmid). The expression of miR-21 was detected by stem-loop real-time reverse transcription (RT)-PCR in OVCAR3 cells, and western blot was used to detect the expression of programmed cell death 4 (PDCD4) protein. Tethyl thiazolyl tetrazolium(MTT) and flow cytometry method were used respectively.Recombinant plasmid (pSIREN-miR-21) was constructed successfully and identified by restriction endonuclease analysis and DNA sequencing. The relative expression level of miR-21 in cells transfection, negative control and blank control group was 0.26 ± 0.08, 1.26 ± 0.21 and 1.00 respectively. The level of miR-21 in the cells in transfection group was significantly lower than those in the negative control and blank control group (P0.01). The gray scale of PDCD4 protein was 1443 ± 33, 858 ± 19 and 846 ± 16 in the transfection group, negative control and blank control group respectively. The value of PDCD4 in transfection group was higher than other control groups, and there were significantly difference among them(P0.01). Moreover, the optical density of the cells in transfection group was 0.661 ± 0.015, significantly lower than those in two control groups (0.848 ± 0.150 for negative control, 0.935 ± 0.133 for blank control, P0.01). Forty-eight hours after transfection, the rate of viable apoptotic cell was significantly higher than negative control and blank control group [(25.821 ± 0.763)% vs. (0.010 ± 0.003)% vs. (0.238 ± 0.023)%; P0.01]; 72 hours after transfection, the rates of viable apoptotic cell and necrotic cell were all higher than the two control groups [the rate of viable apoptotic cell was (30.480 ± 0.821)%, (7.792 ± 0.312)% and (7.033 ± 0.257)% respectively (P0.01); the rate of necrotic cell was (3.558 ± 0.211)%, (1.557 ± 0.067)% and (1.049 ± 0.028)%, respectively (P0.01)].miR-21 might play an important role in the proliferation and apoptosis of ovarian epithelial carcinoma cells through negatively control the expression of PDCD4.

To investigate the expression of microRNA-21(miR-21) in ovarian epithelial carcinoma and its association with the clinicopathological features.The expression of miR-21 was detected by Stem-loop real-time RT-PCR in 48 cases of ovarian epithelial carcinomas, 24 cases of benign ovarian epithelial tumors and 15 cases of normal ovarian tissues.The relative expression level of miR-21(2-(DeltaDelta)CT) was 4.849-/+1.813 in the ovarian epithelial carcinomas, significantly higher than that in the benign ovarian tumors and normal ovarian tissues (P0.01), but comparable between the latter two groups. The expression of miR-21 was not correlated to the histological type, but increased significantly with the progression of the clinical stages and histological grading (P0.01), showing a close correlation to lymphatic metastasis.MiR-21 might play a role as an oncogene in the tumorigenesis and development of ovarian epithelial carcinoma, and is possibly correlated to the progression and prognosis of ovarian epithelial carcinoma.

To investigate the role of matrix metalloproteinase-9 (MMP-9) and tumor necrosis factor-alpha (TNF-alpha) in the pathogenesis of pregnancy-induced hypertension (PIH).The placenta samples were collected from 57 patients with PIH and 24 normal pregnant women. Immunohistochemical staining was used to examine positive expression of MMP-9 and TNF-alpha in these samples.The positive expression of MMP-9 in the normal group was significantly higher than that in patients with moderate or severe PIH (P0.01), while no significant difference was found between normal pregnant women and patients with mild PIH (P0.05), and expression decreased drastically with the progression of PIH (P0.05). The expression of TNF-alpha in the patients with mild, moderate and severe PIH groups were significantly higher than that in the normal group (P0.05, P0.01 and P0.01, respectively), and the differences were also significant between the PIH groups of different severities (P0.01). No correlation was found between MMP-9 and TNF-alpha expressions in the normal and mild PIH groups (r=0.287, P0.05; r=0.382, P0.05), in the patients with moderate and severe PIH, MMP-9 expression showed inverse correlation with TNF-alpha expression (r=-0.563, P0.05; r=-0.681, P0.01).Lowerd MMP-9 expression in syncytiotrophoblast might result in defective nidation in the placenta where local ischemia and hypoxia cause abnormal TNF-alpha elevation, which might be one of the important factors inducing PIH.