Artificial molecular photodiode consisting of GFP/viologen hetero-thin film

By mimicking the biological photosynthesis system, molecular photodiode was developed artificially using molecular array consisting of protein/organic molecular hetero-thin films. Functional organic molecule (viologen) and biomolecules (green fluorescent protein, GFP) were chosen and used as an electron acceptor (A) and the electron sensitizer (S), respectively. Based on the redox potential of each molecules obtained by cyclic voltammetry measurement, molecular thin films were successfully fabricated by aligning the viologen (A) Langmuir–Blodgett film (LB) onto ITO glass and subsequently adsorbing GFP (S) molecules onto the viologen LB film surface. By depositing aluminum (Al) onto GFP/viologen hetero-thin films, a metal/insulator/metal (MIM) structured device was constructed. When the forward bias was applied to the fabricated device in accordance with the energy profile of the prepared thin films, photoswitching function could be obtained.