Photoconductivities of poly[γ‐(β‐N‐carbazolylethyl)‐L‐glutamate] and its charge‐transfer complex with 2,4,7‐trinitrofluorenone

Abstract

AbstractPoly[γ‐(β‐N‐carbazolylethyl)‐L‐glutamate] (PCLG) was prepared by polymerizing the monomer which was synthesized by adapting the NCA method to a reaction product between L‐glutamic acid and N‐(β‐hydroxyethyl)carbazole. PCLG films were prepared on a quartz Nesa (In2O3) plate by casting technique. The charge‐transfer complex could be successfully formed only near the surface of the PCLG film by immersing the PCLG film into either a benzene or a methyl ethyl ketone solution of 2,4,7‐trinitrofluorenone (TNF), since both benzene and methyl ethyl ketone were poor solvents for PCLG and suitable solvents for TNF. A photocell was formed by depositing a translucent gold electrode with vaccum evaporation onto the immersed film. For a small content of TNF in both the immersed films and the homogeneously mixed films of PCLG with TNF, the photocurrent of PCLG was successfully sensitized by TNF, but the sensitized photocurrents retained the relation I>I in a similar way as the photocurrent of PCLG alone, where I was the photocurrent under illumination onto the positive Au electrode and vice versa. On the other hand, as the TNF content increased, I became remarkably greater than I. The PCLG polymer, therefore, can behave as a p‐type photoconductor, while the well‐doped PCLG‐TNF complex can behave as an n‐type photoconductor.