30,647 research outputs found
Addressing the stability issue of perovskite solar cells for commercial applications.
Abstract When translating photovoltaic technology from laboratory to commercial products, low cost, high power conversion efficiency, and high stability (long lifetime) are the three key metrics to consider in addition to other factors, such as low toxicity, low energy payback time, etc. As one of the most promising photovoltaic materials with high efficiency, today organic–inorganic metal halide perovskites draw tremendous attention from fundamental research, but their practical relevance still remains unclear owing to the notorious short device operation time. In this comment, we discuss the stability issue of perovskite photovoltaics and call for standardized protocols for device characterizations that could possibly match the silicon industrial standards
The Minimal Total Irregularity of Graphs
In \cite{2012a}, Abdo and Dimitov defined the total irregularity of a graph
as
\hskip3.3cm
\noindent where denotes the vertex degree of a vertex . In
this paper, we investigate the minimal total irregularity of the connected
graphs, determine the minimal, the second minimal, the third minimal total
irregularity of trees, unicyclic graphs, bicyclic graphs on vertices, and
propose an open problem for further research.Comment: 13 pages, 4 figure
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