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Comparisons between different laboratories on long‐term stability analyses of perovskite solar cells (PSCs) is still lacking in the literature. This work presents the results of an interlaboratory study conducted between five laboratories from four countries. Carbon‐based PSCs are prepared by screen printing, encapsulated, and sent to different laboratories across Europe to assess their stability by the application of three ISOS aging protocols: (a) in the dark (ISOS‐D), (b) under simulated sunlight (ISOS‐L), and (c) outdoors (ISOS‐O). Over 1000 h stability is reported for devices in the dark, both at room temperature and at 65 °C. Under continuous illumination at open circuit, cells survive only for few hours, although they recover after being stored in the dark. Better stability is observed for cells biased at maximum power point under illumination. Finally, devices operate in outdoors for 30 days, with minor degradation, in two different locations (Barcelona, Spain and Paola, Malta). The findings demonstrate that open‐circuit conditions are too severe for stability assessment and that the diurnal variation of the photovoltaic parameters reveals performance to be strongly limited by the fill factor, in the central hours of the day, due to the high series resistance of the carbon electrode. [ABSTRACT FROM AUTHOR]

This review presents a brief history of the development of light sources over the centuries to provide one of the human race’s basic needs – light. Recent moves in Europe to encourage the adoption of compact fluorescent lamps as more energy-efficient replacements for incandescent lights, despite certain drawbacks, are described. Rapid strides are now being made in the development of solid-state ‘white’ lights which are already sufficiently durable and efficient to warrant adoption for both domestic and public lighting purposes. Their basic construction and comparative performance, properties and uses are fully described, together with the many ideas for improving their brightness and durability still further. Solid-state devices offer additional savings compared with those which should be achieved under the EU’s targeted replacement of incandescent lights by 2012, and later one can expect such devices to compete with high-pressure sodium luminaires for street lighting. [ABSTRACT FROM AUTHOR]