Search results for "TPD"
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Space Charge and Carrier Trapping Effects on the Transient Photocurrents of Organic Materials Using the Time-of-Flight Technique
2007
We apply the time-of-flight (TOF) technique to study space charge and carrier trapping effects in the organic materials N,N'-diphenyl-N,N'-bis(3- methylphenyl)-1,1-biphenyl-4,4'-diamine (TPD) and tris(8-hydroxyquinolato) aluminum (Alq3). This is carried out by changing the applied electric field, the laser pulse intensity, and the repetition rate together with environmental conditions in air or in vacuum. We report for the first time, to the best of our knowledge, a clearly nondispersive electron transport in TPD due to the absence of deep traps. Conversely, Alq3 exhibits a dispersive electron transport. However, this can be partially recovered by leaving the sample in high vacuum for sever…
Addressing Complexity in Science|Environment|Health Pedagogy
2019
This paper aims to discuss complexity as a key feature for understanding the role of science knowledge in environmental and health contexts—a central issue in Science|Environment|Health pedagogy. Complex systems are, in principle, not predictable. In different contexts, ephemeral mechanisms produce different, sometimes completely unexpected results. The art of decision-making in complex contexts is to take scientific knowledge into account but to interpret its meaning in terms of concrete complex contexts. This is illustrated by four empirical studies on Science|Environment|Health issues, presented midway through this paper. The findings underscore the importance of introducing complexity i…