Laser ablation at 308 nm for the mixture target of 3,4,9,10-perylenetetracarboxylic dianhydride with Co powder — remarkable enhancement on elimination efficiency of anhydride groups

Abstract

Abstract Mixture targets of 3,4,9,10-perylenetetracarboxylic dianhydride (PTCDA) with Co powder were ablated with XeCl laser beams at various fluences. Structures and electric/electronic properties of deposited films and morphology change of PTCDA/Co targets were investigated by scanning electron micrography (SEM), FT-IR, Raman spectroscopies, electron probe microanalyzer (EPMA), and electric conductivity measurements. As for the mixture target of PTCDA and Co powder (diameter 30 nm) ([PTCDA]/[Co]=1/4), IR spectroscopy showed that fragments without carboxylic dianhydride groups were effectively produced by excimer laser ablation (ELA) at the fluence of more than 1.0 J cm−2 pulse−1. Raman spectra for the films prepared by ELA of the PTCDA/Co target at various fluences obviously showed three peaks at 1600, 1380 and 1290 cm−1, characteristic for polyperinaphthalene (PPN). The film prepared by ELA of PTCDA/Co target at a fluence of 1.0 J cm−2 pulse−1 on a substrate at 20°C consisted of small particles with various diameters ranging from 10 to 100 nm. Only an extremely small amount of Co was detected in the film. Bamboo shoot-like projections could be observed on the PTCDA/Co target surface after irradiation. Co content at the summit was a little bit larger than that at the mountainside. Annealing at 350°C resulted in the increase in electric conductivity up to 1.0×10 −4 S cm −1 , two orders of magnitude higher compared with that before annealing. For the film annealed at 350°C, the presence of a sharp peak at 1290 cm−1 and complete disappearance of 1750 and 1780 cm−1 peaks related to the side groups of PTCDA indicate the formation of better-developed PPN structure.