Posttreatment of titanium oxide (TiO 2 ) using lithium (Li) and cobalt (Co) precursors is widely adopted to modify the charge quenching property in perovskite solar cells (PSCs); however, the fundamental understanding of the effect of the modification layer on the material itself and, consequently, the photovoltaic performance stability is not complete. In this work, in situ X-ray diffraction measurements show that the Li and Co ions can diffuse into TiO 2 and consequently accelerate the rutile phase transformation. X-ray photoelectron spectroscopy results reveal the appearance of a Ti 3+ feature in both the Li-and Co-treated samples, suggesting that the treatment ions are partially located at the subsurface/surface of the spin-cast TiO 2 layer. The Li-treated TiO 2 exhibits greatly upshifted conduction band edges, which benefits charge extraction properties and improves the average device parameters in a complete PSC. To complement the experiments, density functional theory calculations are performed. While Li treatment initially results in enhanced electronic properties, Li-treated TiO 2 tends to have more surface vacancies over time and is more susceptible to adsorption and accumulation of iodide ions compared to the Co-treated sample, which is experimentally supported by surface photovoltage spectroscopy and timeresolved photoluminescence results.

PurposeThis article investigates the dynamic implication of healthcare expenditure on economic growth in the selected ten Sub-Saharan African countries over the period 2000–2018.Design/methodology/approachThe study methodology included dynamic heterogenous panel, using mean group and pooled mean group estimators. The investigation of the healthcare expenditure and economic growth nexus was achieved while controlling the effects of investment, savings, labor force and life expectancy via interaction terms.FindingsThe results from linear healthcare expenditure have a significant positive impact on economic growth, while the nonlinear estimates through the interaction terms between healthcare expenditure and investment have a negative statistically significant impact on growth. The marginal effect of healthcare expenditure evaluated at the minimum and maximum level of investment is positive, suggesting the impact of health expenditure on growth does not vary with the level of investments. This result responds to the primary objective of the article.Research limitations/implicationsIn policy terms, the impact of investment on healthcare is essential to addressing future health crises. The impact of coronavirus disease 2019 (COVID-19) can never be separated from the shortages or low prioritization of health against other sectors of the economy. The article also provides an insight to policymakers on the demand for policy reform that will boost and make the health sector attractive to both domestic and foreign direct investment.Originality/valueGiven the vulnerability of SSA to the health crisis, there are limited studies to examine this phenomenon and first to address the needed investment priorities to the health sector infrastructure in SSA.

No abstract

No abstract

Abstract-This paper investigates the determinants of income of cottage, micro and small scale enterprises (CMSSE S ) in Jigawa State of Nigeria. The research used primary data collected from 300 enterprises drawn from three locations base on stratified random sampling technique. To analysed the data, we used multivariate regression model. The result shows positive relationship between income of the enterprises and education, experience, government support, gender and finance. The policy implication of the study is that policy makers should continue to formulate policies that will support CMSSE S financially in Jigawa State and the country at large.