Two basic, yet different, approaches are available for fabricating elements such as OLEDs or solar cells from thin layers of organic materials with semiconductor properties: namely, (a) the use of polymers, i.e., long-chain molecules that consist of a large number of identical repeating units (monomers) in which the exact number of repeating units in a material is subject to fluctuation, and (b) the use of “small molecules”. This paper compares the two.