Improving the Dielectric Properties of Energy Storage Film Based on Organic Molecular Semiconductor

The energy sector is one of our key areas of focus. Among them, dielectric film capacitors are one of the energy storage devices. Due to their many advantages, they have been widely used in many fields just like in the field of hybrid electric vehicles. There is an urgent demand to develop dielectric film capacitors with higher energy storage capacity. In this paper, in the form of all-organic composite, a small amount of organic semiconductor perylene diimide(PDI) derivative with high electron affinity(EA) was doped into polycarbonate(PC) matrix to improve the breakdown strength. In this way, the energy storage density of dielectric film capacitors will be effectively improved. First of all, the structure of molecular semiconductor perylene diimide derivative and its influence on the chemical structure of PC matrix were characterized by infrared spectroscopy. In order to explore the effect of organic semiconductor doping on the dielectric properties of PC composite films, the dielectric parameters with frequency variation and DC breakdown strength were mainly tested and analyzed. After doping a small amount of perylene diimide derivative with different contents, the dielectric constant of PC composite films has increased to some extent. It is worth stating that the increase of dielectric loss is not significant, which is within an acceptable range. In addition, the DC breakdown test results show that the dielectric film sample doped with 0.001mmol/g perylene diimide derivative can reach 720 MV/m. This is 17% higher than that of pure PC film. Therefore, based on theoretical calculations, the maximum energy storage density at 50Hz will be 1.48 times that of pure PC film.