Woah! The colourful picture - below left - may not look like anything spectacular, but it is the first image of an exciton, captured as it travels through a semiconductor (actually, it's a whole slough of 'em). An 'exciton' is the charge separation generated when a molecule is 'excited' by electromagnetic energy. It consists of an electron - negatively charged - which has been excited to a high energy level, and the 'hole' -positively charged - left behind in the lower energy level where the electron once lived. Think yin and yang, absence and presence, a unity of opposites. It's all very beautiful.
Why get excited about excitons? Well, besides the fact that cool physics is an end unto itself, excitonic transport is at the heart of photosynthesis, the process used by plants to convert sunlight into usable energy. Understanding how it works is the key to building more effective solar cells...and to revolutionizing energy generation.
The clever authors below have taken the first pictures of an exciton as it dances through an organic solar cell. The colours correspond to density of excitons, red being the highest. Time increases vertically upward in the image. We can literally see the excitons spreading out, diffusing through the material! Hopefully this breakthrough will allow us to metaphorically see what's really going on in crucial charge transport processes like photosynthesis.
the efficient transport of photogenerated excitons from the light-harvesting complex of a plant to the reaction centre is at the core of photosynthesis2. Understanding and manipulating the flow of excitons in such systems can enhance device performance5 and can lead to development of next-generation excitonic technologies.