All-Printed Roll-to-Roll Perovskite Photovoltaics Enabled by Solution-Processed Carbon Electrode.

Perovskite photovoltaics have shown great promise in device efficiency but also the promise of scalability through solution-processed manufacture. Efforts to scale perovskites have been taken through printable mesoporous scaffolds and slot die coating of flexible substrates roll-to-roll (R2R). However, to date there has been no demonstration of entirely R2R-coated devices due to the lack of a compatible solution-processable back electrode; instead, high-value evaporated metal contacts are employed as a post process. Here, in this study, the combination of a low-temperature device structure and R2R-compatible solution formulations is employed to make a fully R2R printable device architecture overcoming interlayer incompatibilities and recombination losses. Therefore, the n-i-p device structure of SnO2 /perovskite/poly(3,4-ethylenedioxythiophene)/carbon is employed to form an ohmic contact between a p-type semiconductor and printable carbon electrode. In particular, the results show that the small-scale device efficiencies of 13-14% are achieved, matching the device performance of evaporated gold electrodes. Also, this entirely R2R-coated perovskite prototype represents a game changer, reaching over 10% (10.8) stabilized power conversion efficiency with unencapsulated long-term stability retaining 84% of its original efficiency over 1000 h under 70% RH and 25 °C.

Exploring the Infiltration Features of Perovskite within Mesoporous Carbon Stack Solar Cells Using Broad Beam Ion Milling.

Carbon perovskite solar cells (C-PSCs) are a popular photovoltaic technology currently undergoing extensive development on the global research scene. Whilst their record efficiency now rivals that of silicon PV in small-scale devices, C-PSCs still require considerable development to progress to a commercial-scale product. This study is the first of its kind to use broad beam ion milling for C-PSCs. It investigates how the carbon ink, usually optimised for maximum sheet conductivity, impacts the infiltration of the perovskite into the active layers, which in turn impacts the performance of the cells. Through the use of secondary electron microscopy with energy-dispersive X-ray spectroscopy, infiltration defects were revealed relating to carbon flake orientation. The cross sections imaged showed between a 2% and 100% inactive area within the C-PSCs due to this carbon blocking effect. The impact of these defects on the performance of solar cells is considerable, and by better understanding these defects devices can be improved for mass manufacture.

Cross-talk between vitamin D receptor (VDR)- and peroxisome proliferator-activated receptor (PPAR)-signaling in melanoma cells.

The expression and signaling of the vitamin D receptor (VDR) and peroxisome proliferator-activated receptor (PPAR) alpha, delta, gamma was investigated in the melanoma cell line MeWo. Using real-time PCR, the mRNA of the nuclear receptors (NR) was detected. The strongest expression was found for the VDR, approximately 3-fold higher compared to the expression of PPARalpha or PPARdelta, and the weakest expression was for PPARgamma. After treatment with corresponding ligands, the expression of the VDR, PPARalpha and PPARdelta was elevated up to 5-fold, while the PPARgamma expression was not significantly affected. Treatment with 1alpha,25-dihydroxyvitamin D3 (1,25(OH)2D3, calcitrol) resulted in 40% inhibition of MeWo cell proliferation, that was associated with a 5-fold increase in VDR mRNA. Interestingly, cell proliferation was differentially modulated by treatment with the PPAR ligands. While docosahexaenoic acid (DHA) treatment resulted in a statistically significant increase (approximately 10%), the other PPAR ligands inhibited MeWo cell proliferation. GW501516 (PPARdelta ligand) and WY14643 (PPARalpha ligand) both had an antiproliferative effect of approximately 10%. These antiproliferative effects were not associated with modulation of PPARalpha or PPARdelta expression. In contrast, stimulation of MeWo proliferation by DHA was associated with a 3- and 4-fold increase in the expression of PPARalpha and PPARdelta, respectively. Analyzing the cross-talk between the VDR and PPAR signaling pathways, the 1,25(OH)2D3 treatment resulted in an approximately 2-fold increase in expression of PPARalpha and PPARdelta, while the expression of PPARgamma was unaffected. Treatment with GW501516 and WY14643 resulted in an increase in the VDR expression (2-fold after 120 h). The simultaneous treatment with 1,25(OH)2D3 partially antagonised the DHA- and alpha-linolenicacid (ALA)-induced up-regulation of PPAR expression. In contrast, treatment with the PPAR ligands had no pronounced effect on the 1,25(OH)2D3-induced increase in VDR expression. Simultaneous treatment with the PPAR ligands bezafibrate or ALA resulted in an up to 6-fold reduction of the 1,25(OH)2D3-induced elevation of the 1alpha,25-dihydroxyvitamin D3-24-hydroxylase (CYP24A1) expression. Simultaneous treatment with the PPAR ligands and 1,25(OH)2D3 resulted in only marginal modulation of 1,25(OH)2D3-induced inhibition of cell proliferation. However, simultaneous treatment with bezafibrate and 1,25(OH)2D3 resulted in a statistically significant partial antagonisation of the 1,25(OH)2D3-induced inhibition of MeWo cell proliferation. In conclusion, PPAR and VDR have a role in growth regulation in melanoma cells and functionally relevant cross-talk between these nuclear signaling pathways is indicated, but not at the level of cell proliferation, where 1,25(OH)2D3 has a dominant effect.