Lead-Free Perovskite and Improved Processes and Techniques for Creating Future Photovoltaic Cell to Aid Green Mobility

Perovskites material is in the spotlight as photovoltaic device due to their optical and physical properties. In a short period of time, this organic-inorganic pevskite can achieve about energy conversion efficiencies of 25.6% by anti-solvent and spin-coating based process. In addition, ambipolar carrier transport properties of perovskite materials open up new directions for the high-efficiency thin-film solar cells. Despite its attractive properties in solar cell application, concerned about device stability and the use of lead compounds (APbX3, A = a cation X = halide) with toxicity cause the potential risk for the human body and environment issue. Therefore, the use of a new classed strucutral materials with intrinsic stability and beneficial optoelectronic properties can be considered as a start of the next chapter in pervoksite device. This chapter is structured into two major parts: In section 1, we introduce more stable class of perovskite, A2SnX6, where Sn is in the 4+ oxidation state. A detailed discussion on the ramifications of material structure and chemistry-related challenges is presented for solution processing, along with careful characterization. In section 2, we talk about the direction of development for perovksite materials to be a next chapter of energy source for a green mobility

Optimization of resting tension for wire myography in male rat pulmonary arteries

Abstract Wire myography to test vasomotor functions of blood vessels ex‐vivo are well‐established for the systemic circulation, however, there is no consensus on protocols for pulmonary arteries. We created a standardized wire myography protocol for healthy rat PAs and validated this in a pulmonary hypertension (PH) model. Vessels stretched to higher initial tensions (5.0, 7.5 and 10.0 mN) exhibited a uniform response to phenylephrine, a larger dynamic range, and lower EC50 values. The endothelium‐mediated relaxation showed that moderate tensions (7.5 and 10.0 mN) produced robust responses with higher maximum relaxation and lower EC50 values. For endothelium independent responses, the higher initial tension groups had lower and more consistent EC50 values than the lower initial tension groups. Pulmonary arteries from rats with PH were more responsive to vasoactive drugs when subjected to a higher initial tension. Notably, vessels in the PH group subjected to 15.0 mN exhibited high dynamic ranges in contractile and relaxation responses without tearing. Lastly, we observed attenuated cholinergic responses in these vessels—consistent with endothelial dysfunction in PH. Therefore, a moderate initial tension of 7.5–10.0 mN is optimal for healthy rat pulmonary arteries and a higher initial tension of 15.0 mN is optimal for pulmonary arteries from animals with PH

Simultaneous Enhancement of Electron Injection and Air Stability in N‑Type Organic Field-Effect Transistors by Water-Soluble Polyfluorene Interlayers

Here, we report the simultaneous attainment of efficient electron injection and enhanced stability under ambient conditions for top-gate/bottom-contact (TG/BC), n-type, organic field-effect transistors (OFETs) using water-soluble polyfluorene derivatives (WPFs). When inserting the WPF interlayers between a semiconductor and the BC Au electrodes, initially the ambipolar (6,6)-phenyl-C₆₁butyric acid methyl ester (PCBM) OFETs were fully converted to unipolar charge transport characteristics that were exclusively n-type with significantly increased electron mobilities as high as 0.12 cm²/(V s) and a decreased threshold voltage. These improvements were mostly attributed to the interfacial dipoles of WPF layers that aligned to form a favorable energy band structure for efficient electron injection and to effectively block counter charge carriers. These were confirmed when values for the reduced work function of metal electrodes with WPFs and their correlated contact resistance were measured via the ultraviolet photoemission spectroscopy and the transmission-line method, respectively. Moreover, the WPF interlayers played an important role in air stability of PCBM OFETs that exhibited higher and appreciably enhanced by increasing the ethylene-oxide side chain lengths of WPFs, which presumably was due to the water/oxygen/ion capturing effects in the hydrophilic interlayers

Neonatal exposure to hypoxia induces early arterial stiffening via activation of lysyl oxidases

Abstract Hypoxia in the neonatal period is associated with early manifestations of adverse cardiovascular health in adulthood including higher risk of hypertension and atherosclerosis. We hypothesize that this occurs due to activation of lysyl oxidases (LOXs) and the remodeling of the large conduit vessels, leading to early arterial stiffening. Newborn C57Bl/6 mice were exposed to hypoxia (FiO2 = 11.5%) from postnatal day 1 (P1) to postnatal day 11 (P11), followed by resumption of normoxia. Controls were maintained in normoxia. Using in vivo (pulse wave velocity; PWV) and ex vivo (tensile testing) arterial stiffness indexes, we determined that mice exposed to neonatal hypoxia had significantly higher arterial stiffness compared with normoxia controls by young adulthood (P60), and it increased further by P120. Echocardiography performed at P60 showed that mice exposed to hypoxia displayed a compensated dilated cardiomyopathy. Western blotting revelated that neonatal hypoxia accelerated age‐related increase in LOXL2 protein expression in the aorta and elevated LOXL2 expression in the PA at P11 with a delayed decay toward normoxic controls. In the heart and lung, gene and protein expression of LOX/LOXL2 were upregulated at P11, with a delayed decay when compared to normoxic controls. Neonatal hypoxia results in a significant increase in arterial stiffness in early adulthood due to aberrant LOX/LOXL2 expression. This suggests an acceleration in the mechanical decline of the cardiovascular system, that contributes to increased risk of hypertension in young adults exposed to neonatal hypoxia that may increase susceptibility to further insults

The Effect of Fluorine Substitution on the Molecular Interactions and Performance in Polymer Solar Cells

Fluorine (F) substitution on conjugated polymers in polymer solar cells (PSCs) has a diverse effect on molecular properties and device performance. We present a series of three D-A type conjugated polymers (PBT, PFBT, and PDFBT) based on di­thieno­thio­phene and benzo­thia­diazole units with different numbers of F atoms to explain the influence of F substitution by comparing the molecular interactions of the polymers and the recombination kinetics in PSCs. The preaggregation behavior of PFBT and PDFBT in <i>o</i>-DCB at the UV–vis absorption spectra proves that both polymers have strong intermolecular interactions. Besides, more closely packed structures and change into face-on orientation of fluorinated polymers are observed in polymer:​PC₇₁BM blends by GIXD which is beneficial for charge transport and, ultimately, for current density in PSCs (4.3, 13.0, and 14.5 mA cm^–2 for PBT, PFBT, and PDFBT, respectively). Also, the introduction of F atoms on conjugated backbones affects the recombination kinetics by suppressing bimolecular recombination, thereby improving the fill factor (0.41, 0.68, and 0.69 for PBT, PFBT, and PD­FBT, respectively). Consequently, the PCE of PSCs reached 7.3% without any additional treatment (annealing, solvent additive, etc.) in the polymer containing difluorinated BT (PD­FBT) that is much higher than nonfluorinated BT (PBT ∼ 1%) and monofluorinated BT (PFBT ∼ 6%)