Role of Band-Structure Approach in Biohybrid Photovoltaics—A Path Beyond Bioelectrochemistry

Emulation of natural photosynthesis is central to modern photovoltaic research eying sustainable and economic ways of solar energy harvesting. Natural photosynthetic systems have succeeded in efficiently harvesting solar energy which is key to the sustenance of life on earth. With numerous advances in understanding the structure and function of the natural photosystems, the last decade has witnessed new perspectives in developing Bio-inspired Photovoltaics. Interestingly, Organic Photovoltaics (OPVs) adopting photosynthetic design principles and Biohybrid Photovoltaics (BPVs) adopting solid-state device architectures have now converged at a juncture. Several reports in the past few years point to a new scope of improvement in OPVs and BPVs stemming from mutual inspiration. At this juncture, there are new perspectives by which a BPV can be designed that were previously limited only to the conventional optoelectronics. Treating natural photosynthetic pigment-proteins as optically- and electronically-functional materials in any photovoltaic design, from the band-theory viewpoint, is a promising direction for advancing BPVs beyond the boundaries of Bioelectrochemistry. This chapter presents an overview of selected reports on BPVs in the recent years utilizing new design concepts based on band-theory and its associated principles. In light of this, the scope of band-structure approach in BPVs is discussed eliciting prospective research directions.