Q: How does quantum confinement in nanowires affect the electronic and optical properties - and how can these effects be manipulated to create novel devices such as LEDs or solar cells?
The quantum confinement in nanowires or the size effect depends on the shape and size of the nanowires: length, diameter, sprouts, wavy shape changes...
Yes, absolutely. Confinement occurs when the dimensions of the nanowire (esp. its radius) are reduced to ~10 nm, restricting the motion of electrons and holes to dimensions that are on the order of their de Broglie wavelength.
Regarding electronic phenomena, this can have implications on the band gap, and carrier mobility. Pragmatically, enhanced sensitivity in devices is a useful feature that can be exploited from these effects.