Drop-casted Photosystem I/cytochrome c multilayer films for biohybrid solar energy conversion

One of the main barriers to making efficient Photosystem I-based biohybrid solar cells is the need for an electrochemical pathway to facilitate electron transfer between the P-700 reaction center of Photosystem I and an electrode. To this end, nature provides inspiration in the form of cytochrome c(6), a natural electron donor to the P-700 site. Its natural ability to access the P-700 binding pocket and reduce the reaction center can be mimicked by employing cytochrome c, which has a similar protein structure and redox chemistry while also being compatible with a variety of electrode surfaces. Previous research has incorporated cytochrome c to improve the photocurrent generation of Photosystem I using time consuming and/or specialized electrode preparation. While those methods lead to high protein areal density, in this work we use the quick and facile vacuum-assisted drop-casting technique to construct a Photosystem I/cytochrome c photoactive composite film with micron-scale thickness. We demonstrate that this simple fabrication technique can result in high cytochrome c loading and improvement in cathodic photocurrent over a drop-casted Photosystem I film without cytochrome c. In addition, we analyze the behavior of the cytochrome c/Photosystem I system at varying applied potentials to show that the improvement in performance can be attributed to enhancement of the electron transfer rate to P-700 sites and therefore the PSI turnover rate within the composite film.

Automated summary

One of the main challenges in developing efficient Photosystem I-based biohybrid solar cells is the lack of an electrochemical pathway for efficient electron transfer. This study utilizes cytochrome c as an electron donor to the P-700 site in Photosystem I, mimicking nature's inspiration. The researchers use a vacuum-assisted drop-casting technique to create a Photosystem I/cytochrome c composite film, demonstrating improved cathodic photocurrent due to enhanced electron transfer rate within the film.