Electron beam modified zinc phthalocyanine thin films for radiation dosimeter application

- Modification of ZnPc films was carried out by exposing them to high energy electron beam of different doses.
- Linear enhancement of electrical conductance was observed with dose.
- Systamatic lowering of chemi-resistive response (towards ppm level of H2S gas) was observed with dose.
- The modification of electrical conductance and gas sensing response suggests possible application of ZnPc films as radiation dosimeter.

Present study deals with the effect of electron beam irradiation on electrical and gas sensing properties of zinc phthalocyanine (ZnPc) thin film prepared on flexible Biaxially Oriented Polyethylene Terephthalate (BOPET) sheet. The electron beam irradiation of ZnPc films were carried out using a 10 MeV RF Linear accelerator, under different radiation dose levels from 1 kGy to 30 kGy. The pristine and irradiated films were characterized by using X-ray photoelectron spectroscopy, Atomic Force microscopy, UV-vis spectroscopy and X-ray diffraction. Samples irradiated in the dose range of 1-18 kGy exhibit linear enhancement of electrical conductance due to increasing content of adsorbed oxygen. Beyond 18 kGy the sample exhibit saturation in the content of adsorbed oxygen as well as in electrical conductance. The pristine ZnPc films exhibit excellent chemi-resistive response towards H2S gas in 1-20 ppm range at room temperature. The response of the irradiated films decreases monotonically with increasing electron beam dose due to the strong binding of oxygen at the Zn sites. A plausible mechanism of electron beam induced modification of ZnPc films and its implication on charge transport as well as chemi-resistive gas sensing behavior are discussed. This work highlight the utilization of ZnPc thin films as potential radiation dosimeter based upon linear rise in electrical conductance.

Exposure of ZnPc films to different doses of electron beam (10 MeV) leads to a linear rise in the electrical conductance due to enhancement in content of adsorbed oxygen, suggesting their possible application as radiation dosimeter.242