Electronic polarization at surfaces and thin films of organic molecular crystals: PTCDA

The electronic polarization energies, P=P++P−, of a perylenetetracarboxylic acid dianhydride (PTCDA) cation and anion in a crystalline thin film on a metallic substrate are computed and compared with measurements of the PTCDA transport gap on gold and silver. Both experiments and theory show that P is 500 meV larger in a PTCDA monolayer than in 50 Å films. Electronic polarization in systems with surfaces and interfaces are obtained self-consistently in terms of charge redistribution within molecules.