Seyedeh Shabnam Daryabari - Department of Chemistry, Faculty of Science , Azad University Central Tehran Branch , Center Tehran Branch, Tehran;
Javad Beheshtian - Department of Chemistry, Faculty of Science, Shahid Rajaee Teacher Training University, P.O. Box: ۱۶۸۷۵-۱۶۳, Tehran, Iran
Sakineh Mansouri - Department of chemistry , Faculty of Science,Islamic Azad University, Central Tehran Branch, Tehran

Graphene quantum dots (GQDs) [1-4] are a few atoms thick graphene and their size is less than 30 nm. GQDs possess excellent features such as large diameter, high surface area, and good surface grafting using conjugated π-π network and other physical properties [5]. These properties include highly tunable photoluminescence, remarkable UV-blocking property, good biocompatibility, unique spin property, and high photo stability. It possesses a wide range of applications in ion detection, bio-imaging, photo catalysts, photo detectors, electrochemical luminescence, optical sensors and photovoltaic devices [6, 7].Doping of graphene and GQDs with heteroatoms has led to improve their catalytic activities towards oxidation-reduction reactions which are a requisite for energy storage or conversion. We designed a porous graphene and doped them with N. in this defected central C6 was deleted and one crown of C6 unit saturated with 3N atoms were used. The resulting structure can be described to that of the molecule without its central C6 atoms is C87H24N3. we analyzed the interaction energy and properties of Helium on defective graphene sheet in present of electric field were investigated by means of first-principles based on density functional theory. All DFT calculations performed using Gaussian 09 package at the M062X/6-31G* computational level of theory. Our results show that the He optimized energy value on doped graphene and band gap decreased when electric field rises.