Temperature- and Component-Dependent Degradation of Perovskite Photovoltaic Materials under Concentrated Sunlight

We report on accelerated degradation testing of MAPbX3 films (X = I or Br) by exposure to concentrated sunlight of 100 suns and show that the evolution of light absorption and the corresponding structural modifications are dependent on the type of halide ion and the exposure temperature. One hour of such exposure provides a photon dose equivalent to that of one sun exposure for 100 hours. The degradation in absorption of MAPbI3 films after exposure to 100 suns for 60 min at elevated sample temperature (∼45-55 °C), due to decomposition of the hybrid perovskite material, is documented. No degradation was observed after exposure to the same sunlight concentration but at a lower sample temperature (∼25 °C). No photobleaching or decomposition of MAPbBr3 films was observed after exposure to similar stress conditions (light intensity, dose, and temperatures). Our results indicate that the degradation is highly dependent on the hybrid perovskite composition and can be light- and thermally enhanced

Traditional media use and depression in the general population: evidence for a non-linear relationship

© 2018, Springer Science+Business Media, LLC, part of Springer Nature. Depression is the most common metal disorder linked to media use. Theoretically, the relationship between depression and media use has been conceptualized as a linear function. However, depressive symptoms vary from dysphoric moods to severely depressed states with major social impairment, thus providing a strong alternative rationale for a non-linear relationship. This paper reports on findings from a representative telephone survey of the general German population (N = 2002) including both the respondents’ motivation behind spending time using traditional media and a measure to screen for depression in the general population. The curve-fitting methodology revealed that the associations between depression and media use are described by a cubic growth function for newspapers, the radio, magazines, and books; associations with television use were positive, but more complex. The relationship between depression and media use should be modeled as a polynomial function for more accurate estimations in the future.status: Published onlin