Photocurrent characteristics of ferrocene/flavin/viologen/TCNQ heterojunction

A molecular photodiode was fabricated with the hetero-langmuir-Blodgett (LB) film consisting of an electron donor (D), sensitizer (S), relay (R) and acceptor (A). Ferrocene, flavin, viologen and TCNQ were used as D, S, R and A units, respectively. By aligning hetero-LB film of D/S/R/A units on ITO glass with an aluminum thin film, a molecular photodiode with the structure of Metal/Insulator/Metal (MIM) was constructed. Due to excitation by irradiation with a 460 nm monochromatic light source, the photoswitching function was observed. And action spectrum of MIM device was measured. To investigate the photoswitching time and charge transport rate, transient photocurrent of MIM device was measured. Result shows that efficient charge transport from D to A in the heterojunction was occurred due to the existence of R and less recombination.