Photoconductivity of Aliphatic Polyimide.

Photoconductivity of an aliphatic polyimide, PI(PMDA/DCHM), was investigated, comparing with that of an aromatic polyimide, PI(PMDA/ODA). An enhanced photocurrent was observed for the aliphatic polyimide. The quantum efficiency of the aliphatic polyimide and the aromatic polyimide was 2.1×10-5 at 370nm, as 5.6×10-6 at 420nm respectively, where the film thickness is 1.0μ. Initial photoresponse behavior was observed to investigate the photoconduction mechanism of the aliphatic polyimide, which shows a different behavior from the aromatic polyimide. The nature of the aliphatic polyimide film is investigated by using the model compounds. The emission spectra of the aliphatic polyimide shows the red-shifting with increasing of the excitation intensity, which indicates the existence of an aggregation of pyromellitic groups intra-and intermolecularly.