Solution processed small molecule organic interfacial layers for low dark current polymer photodiodes

We demonstrate a small molecule solution processed hole interfacial layer approach to improve the dark current characteristics of polymer photodiodes. The two hole blocking materials under investigation 3-phenyl-4(1'-naphthyl)-5-phenyl-1,2.4-triazole (TAZ) and 2-[3,5-bis(1-phenylbenzimidazol-2-yl)phenyl]-1-phenylbenzimidazole (TPBi) are spincoated from ethanol as an orthogonal solvent on top of a P3HT:PCBM active layer. We reduce the dark current at a bias voltage of -1 V by a factor of 17.2 by introducing a TAZ interfacial layer while keeping the responsivity unchanged. (C) 2012 Elsevier B.V. All rights reserved.