Carbon nanomaterials for photovoltaic process

Abstract

Carbon nanomaterials, such as fullerene, carbon nanotubes (CNTs), and graphene, are competitive candidate materials for photovoltaic (PV) applications. Fullerenes and their derivatives have tunable energy levels and high mobilities, which makes them the most popular electron acceptors for organic solar cells (OSCs). Tailoring the energy levels and packing behaviors of fullerenes by well-designed chemical modification is essential to improve the performance of fullerene-based electron acceptors. Semiconducting single-walled CNTs can play similar roles in OSCs. Owing to the extremely high mobilities, CNTs and graphene are incorporated as charge transport materials. They are also promising candidates for transparent electrodes, especially in flexible PV devices. Besides OSCs, CNT and graphene films can form heterojunctions with inorganic semiconductors and CNTs themselves can also form bipolar diodes by using asymmetrical metallic contacts. Solar cells based on these kinds of junctions exhibit high efficiencies and can be multiplied to obtain higher voltages and currents. By further optimizing the molecular design and methods for preparation, handling and assembling of carbon nanomaterials, performance of the PV devices can be further improved. Then the real application of carbon nanomaterials in PV devices is expected.