Charge transport across pressure-laminated thin films of molecularly doped polymers

Discrete interfaces between successive layers in an organic semiconducting device simplify any examination of interface barriers for charge transport. To form discrete interfaces between organic layers we propose lamination as an alternate approach to physical vapor deposition. Transient photocurrent measurements as a function of pressure, thickness, and electric field were performed on cells of 1,1-bis[(di-4-tolylamino)phenyl]-cyclohexane (TAPC), N,N-bis(3,4-dimethylphenyl)-4-aminobiphenyl (DMPAB), and N,N’-diphenyl-N,N’-bis(3-methylphenyl)-[1,1’-biphenyl]-4,4’-diamine (TPD). It was found that, in the range 0.8–3.0 MPa, a pressure-laminated interface between two identical materials causes no measurable perturbation to charge transport. This justifies the use of pressure lamination to study interfaces between nonidentical layers.