Emulation of natural photosynthesis is central to modern photovoltaic research targeting 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 bioinspired photovoltaics. Interestingly, organic photovoltaics (OPVs) adopting photosynthetic design principles and biophotovoltaics (BPVs) adopting solidstate device architectures have now converged at a juncture. Several reports in recent 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 conventional optoelectronics. Treating natural 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 article presents an overview of selected reports on BPVs in the last few years utilizing new design concepts based on band-theory and its associated principles. In light of this, the scope of the band-structure approach in BPVs is discussed, eliciting prospective research directions.

Energy self-sufficiency is an inspirational design feature of biological systems that fulfills sensory functions. Plants such as the "touch-me-not" and "Venus flytrap" not only sustain life by photosynthesis, but also execute specialized sensory responses to touch. Photosynthesis enables these organisms to sustainably harvest and expend energy, powering their sensory abilities. Photosynthesis therefore provides a promising model for self-powered sensory devices like electronic skins (e-skins). While the natural sensory abilities of human skin have been emulated in man-made materials for advanced prosthetics and soft-robotics, no previous e-skin has incorporated phototransduction and photosensory functions that could extend the sensory abilities of human skin. A proof-of-concept bioelectronic device integrated with natural photosynthetic pigment-proteins is presented that shows the ability to sense not only touch stimuli (down to 3000 Pa), but also low-intensity ultraviolet radiation (down to 0.01 mW cm ) and generate an electrical power of ≈260 nW cm . The scalability of this device is demonstrated through the fabrication of flexible, multipixel, bioelectronic sensors capable of touch registration and tracking. The polysensory abilities, energy self-sufficiency, and additional nanopower generation exhibited by this bioelectronic system make it particularly promising for applications like smart e-skins and wearable sensors, where the photogenerated power can enable remote data transmission.

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