What sort of molecules or polymers are used in OLED displays?
A typical organic light emitting diode (OLED) structure consisting of a glass substrate, a indium titanium oxide (ITO) anode, and an organic bilayer diffused into a metallic cathode, is given below:



The organic bilayer consists of:


a hole transport layer (HTL), typically of N, N'-diphenyl-N, N'-bis(3-methylphenyl) 1, 1'-biphenyl-4, 4' diamine (TPD) or N,N′-di(naphthalene-1-yl)-N,N′- diphenylbenzidine (NPB)
an emitting/electron transport layer (EML/ETL), typically of tris(8- hydroxyquinoline) aluminum (Alq3)


Source: http://espace.library.uq.edu.au/eserv.php?pid=UQ:8598&amp;dsID=SMS.pdf