Carbon Quantum Dots in Novel Photosystem I-Based Photovoltaics for Enhanced Photocurrent

Abstract

Although modern photovoltaics have reached internal quantum efficiencies greater than 50%, it has come at the expense of requiring extensive synthetic conditions and materials harmful to the environment. As an alternative, our group has turned to a class of bioinspired photovoltaics using Photosystem I (PSI), a robust membrane protein complex found in plants, to generate photocurrent when interfaced with semiconductive materials. Although functional PSI devices have been made using a variety of materials (silicon wafers, nanoporous gold, graphene) they often require extensive processing of the materials and harsh experimental conditions. Furthermore, the observed photocurrent densities tend to suffer from poor contact at the protein-electrode interface. In this work, an emerging class of carbon semiconductors, carbon quantum dots (CQDs), will be synthesized to promote charge separation in PSI photovoltaic cells. Through a facile, one-step solvothermal synthesis, CQDs electronically compatible with PSI can be made from common carbon precursors and novel small molecule dopant sources, cutting the cost and environmental impact of our devices. Following purification, the as produced CQDs exhibit tunable band energetics as a result of varied synthetic conditions allowing for precise band alignment. Thanks to their small size and modifiable carbon surface, CQDs are compatible with a number of coupling strategies allowing for a more uniform PSI-CQD interface, potentially enhancing the observed photocurrent densities. This study will open the door to a low-cost, organic photovoltaic whose fabrication could generate significantly higher photocurrent, easily be scaled-up or used in non-laboratory settings.