Inverted pyramidally-textured PDMS antireflective foils for perovskite/silicon tandem solar cells with flat top cell.

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Perovskite/silicon tandem solar cells with high theoretical efficiency, low cost, and the potential for simple mass production have received significant attention. To maintain the current matching, increasing the open-circuit voltage (V OC) of the top and bottom subcells is an effective route to enhance the efficiency of tandem solar cells (TSCs). In this paper, we focus on a strategy for increasing the V OC and simultaneously maintaining a high efficiency of over 20%. Perovskite thin films with added Cs in traditional FAMA cations have shown a large grain, smooth surface morphology, wider band gap, and reduced defects, which together bring about a TSC V OC of 1.78 V. In addition, the high minority carrier lifetime (τeff) of bottom silicon solar cells resulting from the good passivation of a-Si:H/c-Si interface enhance the V OC values to as high as 1.83 V, which is the highest value for perovskite/silicon TSCs.

Owing to their rational distribution and adequate use of the solar spectrum and a high open-circuit voltage, perovskite/silicon-heterojunction (SHJ) tandem solar cells can exceed the theoretical limit of efficiency for crystalline silicon solar cells. To improve the performance of perovskite/SHJ tandem solar cells, the distribution of the solar spectrum and current matching between sub-cells must be examined and optimized. This study employs mixed perovskite as the top cell, which is prepared with pure N, N-dimethyl formamide (DMF), pure dimethyl sulfoxide (DMSO), and mixtures of these components in different volume ratios. The effect of different solvents on surface structure and the photoelectric properties of FACs perovskite materials are systematically examined. When the volume fraction of DMSO is 40%, a smooth, well passivated, high-quality perovskite film is obtained. Most importantly, light absorbance and transmittance are balanced by applying solvent engineering to optimize perovskite films in the tandem devices. This method can be further extended to a more complicated FAMACs perovskite/SHJ by delivering a power conversion efficiency of 22.80%. This study concludes that solvent engineering is an effective and simple method for modifying the performance of monolithic perovskite/ silicon tandem devices.

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Background and purposeSignal transducer and activator of transcription 3 (STAT3) may contribute to the proinflammation in the central nervous system diseases by modulating the microglial responses. Thus, this study was intended to investigate the effect of STAT3 on microglia-dependent neuroinflammation and functional outcome after experimental subarachnoid haemorrhage (SAH).MethodsThe SAH model was established by endovascular perforation in the mouse. Real-time PCR (RtPCR) and western blot were used to examine the dynamic STAT3 signalling pathway responses after SAH. To clarify the role of the STAT3 signalling pathway in the microglia-dependent neuroinflammation after SAH, the microglia-specific STAT3 knockout (KO) mice were generated by the Cre-LoxP system. The neurological functions were assessed by Catwalk and Morris water maze tests. Neuronal loss after SAH was determined by immunohistochemistry staining. Microglial polarisation status after STAT3 KO was then examined by RtPCR and immunofluorescence.ResultsThe STAT3 and Janus kinase-signal transducer 2 activated immediately with the upregulation and phosphorylation after SAH. Downstream factors and related mediators altered dynamically and accordingly. Microglial STAT3 deletion ameliorated the neurological impairment and alleviated the early neuronal loss after SAH. To investigate the underlying mechanism, we examined the microglial reaction after STAT3 KO. STAT3 deletion reversed the increase of microglia after SAH. Loss of STAT3 triggered the early morphological changes of microglia and primed microglia from M1 to M2 polarisation. Functionally, microglial STAT3 deletion suppressed the SAH-induced proinflammation and promoted the anti-inflammation in the early phase.ConclusionsSTAT3 is closely related to the microglial polarisation transition and modulation of microglia-dependent neuroinflammation. Microglial STAT3 deletion improved neurological function and neuronal survival probably through promoting M2 polarisation and anti-inflammatory responses after SAH. STAT3 may serve as a promising therapeutic target to alleviate early brain injury after SAH.

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Background Intracranial aneurysms are increasingly being treated by the placement of flow diverters; however, the factors affecting the outcome of aneurysms treated using flow diverters remain unclarified. Methods The present study investigated 94 aneurysms treated with pipeline embolisation device placement, and used a computational fluid dynamics method to explore the factors influencing the outcome of aneurysms. Results Seventy-six completely occluded aneurysms and 18 incompletely occluded aneurysms were analysed. Before treatment, inflow jets were found in 13 (72.2%) aneurysms in the incompletely occluded group and 34 (44.7%) in the completely occluded group ( P = 0.292). After deployment of the pipeline embolisation device, inflow jets remained in nine (50%) aneurysms in the incompletely occluded group and nine (11.8%) in the completely occluded group ( P = 0.001). In the incompletely occluded group, regions with inflow jets after treatment corresponded with the patent areas shown on follow-up digital subtraction angiography. The mean reduction ratios of velocity in the whole aneurysm and on the neck plane were lower in the incompletely occluded than in the completely occluded group ( P = 0.003; P = 0.017). Multivariate analysis revealed that the only independent risk factors for incomplete aneurysm occlusion were the reduction ratios of velocity (in the whole aneurysm, threshold 0.362, P = 0.005; on the neck plane, threshold 0.273, P = 0.015). Conclusions After pipeline embolisation device placement, reduction ratios of velocity in the whole aneurysm of less than 0.362 and on the neck plane of less than 0.273 are significantly associated with a greater risk of aneurysm incomplete occlusion. In addition, the persistence of inflow jets in aneurysms is associated with incomplete occlusion in the inflow jet area.