Effects of alkali and transition metal-doped TiO2 hole blocking layers on the perovskite solar cells obtained by a two-step sequential deposition method in air and under vacuum

Planar perovskite solar cells (PPSCs) have received great attention in recent years due to their intriguing properties, which make them a good choice for photovoltaic applications. In this work, the effect of alkali and transition metal-doped TiO₂ (cesium-doped TiO₂ (Cs-TiO₂) and yttrium-doped TiO₂ (Y-TiO₂)) compact layers on the optical, structural and the photovoltaic performance of the PPSCs have been investigated. The perovskite layer syntheses were carried out by depositing a lead iodide (PbI₂) layer via spin-coating; converting PbI₂ into methyl ammonium iodide (CH₃NH₃PbI₃) by chemical vapor deposition (CVD) and spin-coating at 60 min and 60 s conversion times respectively. The as-deposited PPSCs were studied layer-by-layer using an X-ray diffractometer, scanning electron microscope, and UV-vis diffuse reflectance, transmittance and absorbance. The power conversion efficiency for stable processed perovskite solar cells were 3.61% and 12.89% for air and vacuum processed, respectively.

Planar perovskite solar cells (PPSCs) have received great attention in recent years due to their intriguing properties, which make them a good choice for photovoltaic applications.

Comparison between olfactory function of pregnant women and non-pregnant women in reproductive age group in Ibadan, Nigeria

BACKGROUND

Pregnant women require normal olfactory function in order to develop good appetite for healthy living and normal fetal development. This study was carried out to investigate and compare olfactory function of pregnant women with non-pregnant women.

METHODS

This was a case control study of women in reproductive age group at the University College Hospital, Ibadan, Nigeria from July 2014 to February 2015. Consecutive 70 pregnant women and 70 non-pregnant women (controls) without rhinologic symptoms were studied. A structured questionnaire was administered to obtain participants' information on socio-demographics, pregnancy history, and ability to perceive smell. They subjectively rated their olfactory function on a visual analogue scale of 0 - 100. Olfactory threshold (OT), discrimination (OD), identification (OI) scores and TDI of both groups were determined with"Sniffin' sticks"kits and compared. The level of significance was P<0.05.

RESULTS

The mean age of the pregnant women was 30.5±3.9years and control was 28.5±6.6years. There were more pregnant women (7.1%) with hyposmia than the non-pregnant women (2.9%). The subjective rating of olfactory function was 68.2±24.9 (median 70) and 72.3±21.6 (median 69) in pregnant women and controls respectively. The mean OT, OD, OI, TDI scores were higher in pregnant women than the controls. However, it was only in OI (P=0.000) and TDI (P=0.012) that the differences were significant.

CONCLUSIONS

Pregnant women have olfactory dysfunction more than the non-pregnant women of reproductive age group. Also, they have tendency to develop loss of cognitive olfactory information more than the non-pregnant women.

Orbital control of noncollinear magnetic order in nickel oxide heterostructures

We have used resonant x-ray diffraction to develop a detailed description of antiferromagnetic ordering in epitaxial superlattices based on two-unit-cell thick layers of the strongly correlated metal LaNiO3. We also report reference experiments on thin films of PrNiO3 and NdNiO3. The resulting data indicate a spiral state whose polarization plane can be controlled by adjusting the Ni d-orbital occupation via two independent mechanisms: epitaxial strain and spatial confinement of the valence electrons. The data are discussed in light of recent theoretical predictions.