Beyond the Plane: Boosting Photosystem I Biophotocathode Performance with 3D Folded and Stacked Architectures

High Resolution Image Download MS PowerPoint Slide The investigation of biophotoelectrochemical devices is often constrained to the use of planar electrodes of small dimensions limiting the density of photoactive sites. To maximize incident light utilization, practical devices require packing of photoactive elements in a confined space, minimizing the device’s footprint. However, tridimensional electrode architectures bring new challenges to take into consideration ensuring adequate photoexcitation of the complete device. Here, we investigate the use of folded and stacked tridimensional architectures of photosystem I (PSI)-based biophotocathodes. Electrodes modified with PSI embedded in a redox polymer film were studied at varying angles relative to the illumination source. Reflective substrates enhance photocurrent via light reflection, whereas transparent electrode substrates mitigate shading effects. Stacking transparent electrodes proportionally increases the total photocurrent by enabling light penetration through the multiple active layers, while ensuring fast electron transfer between PSI and the electrode. The importance of tridimensional electrode design is illustrated with a flexible device, which delivers a superior photocurrent density compared to its planar counterpart. This work elucidates fundamental design principles for using 3D-electrode architectures and substrate optics to develop compact, flexible, and high-performance bio-optoelectronic devices, with broad implications for solar-to-chemical energy conversion systems.