Diodes based on bilayers comprising of tetraphenyl porphyrin derivative and fullerene for hybrid nanoelectronics

We demonstrate synthesis of diodes based on donor–acceptor bilayers consisting of fullerene (C60) and tetraphenyl porphyrin derivative, that is, 5,10,15,20 tera(3-fluorophenyl)-porphyrin (TFPP), grafted on Si. These bilayer diodes were synthesized in two steps: (i) electrografting of a ∼3.5 nm C60 layer on H-terminated Si and (ii) deposition of TFPP layers on C60 layer by self-assembly process. Fourier-transform infrared spectroscopy data show that C60 layer forms a supramolecular complex with TFPP at the interface. The current rectification ratio (defined as: RR = |I−1.8V/|I+1.8V) for TFPP/C60 molecular diodes was ∼1500. The rectification behavior has been understood using the ab initio molecular-orbital theoretical calculations.