I don't have a pair of cans (you know, those huge headphones from the seventies), but if i did i would be worried about the amount of energy they would consume and the effect of such consumption on the battery life of the device they are plugged into.
Part of the design of over-ear headphones, the strap at the top might be a perfect place to put a DSSC type solar collector. It would be minimally visible and might be capable of generating enough power to amplify the sound in the headphones with out drawing on the device's battery too heavily.
Please, if someone smarter than I am works out the math to see if it is viable and develops it as a product, could you send me a pair for coming up with the idea?
On a greener note. Roof tops world wide have a range of options for durable covering. Some "permanent" roofing solutions can be quite expensive. How close would a DSSC doped roofing comp be to the price of higher end comp roofs? What I am thinking is, for the longest time people have been trying to make solar compact and efficient. Well, why? With hundreds of available square feet on every roof top, capable of generating even low voltage for a secondary lighting system or climate controls, the net gain would be much greater on a large scale than convincing home owners to purchase expensive stand alone systems.
Doped comp could be deployed much like regular comp, only with a copper band under it placed in such a way that the act of nailing the comp down would complete the circuit. A diode placed at the end of each band (near the eves of the house) tying the system together but preventing one bad tile from ruining more than a row. It would not have to be very efficient for it to be functional.
I came to this thought by thinking about how plants produce energy. they do not do it my having overly efficient systems, most of the space inside a chloroplast is empty, even most of the surface of a thylakoid inside is simple cell membrane. So how do they support so much of life on earth? with overwhelming numbers. Millions of photo-systems per leaf, millions of chloroplasts per plant, millions of plants on the planet, until the amount of potential energy created in a single instant is mind boggling. As opposed to one central mechanism that creates energy for a group of trees (like the model we have for power distribution).
Another benefit would be energy stability. A leaf can be removed from a tree with out the tree immediately dying. If we lose a power generating station, our grid is significantly effected. In my decentralized model, if one house burns down, very few other houses (if any) will notice an effect to their power.