In this thesis Coulomb blockade effect is studied for a system composed of organic molecules and quantum dots. We use the tight binding h Hamiltonian to obtain Green function, which is derived from second quantization and Heisenberg equations of motion for creation and annihilation operators by including electron-electron interaction. The electrodes’ self-energy is taken into account by using expansion of the Green function in term of the Hamiltonian wave function. Transmission function and density of states at two different device situations: neutral and charged structure are calculated. we depict the potential across device by Jacobi method and the current by Landuer formula, Moreover we calculate switching bias. Inserting quantum dots between organic molecules increases conduction at Fermi energy level. Eventually, we describe the break down of the Coulomb blockade due to the replacement energy levels and the hopping term between the nearest neighbours. we indicate this work increases conduction at Fermi energy level.
