Rectified photocurrent of the protein-based bio-photodiode

A bio-photodiode was fabricated using an array of electronically functional molecular layers, which consisted of a thin film of the green fluorescent protein and organic hetero-Langmuir–Blodgett layers between metal electrodes. With repeated step light illumination, the photocurrent was generated accordingly, which indicates a photoswitching function. Under illumination, the rectified photocurrent of the bio-photodiode was observed from current–voltage measurements. To verify the switching function and charge transfer through the functional molecular layers, transient photocurrents were measured. In transient photocurrent measurements, unidirectional charge flows generated by the redox potential difference through the molecular layers were observed.