8. Toward All-Carbon Hybrid Solar Cells

As one of p-type semiconductors with direct bandgap, semiconducting single-walled carbon nanotubes (sc-SWCNTs) possess ultrahigh carrier mobility, unique electron structures, high light absorption coefficient and other physical properties, which have been widely used in novel photodetectors and photovoltaic devices. While fullerenes are typical n-type semiconductors and metallic SWCNTs (or graphene) usually behave as carrier transport channel due to the high carrier mobility. Taking advantage of the excellent physical properties of different carbon nanomaterials, a new concept photovoltaic device, all-carbon solar cell, is expected to be developed by combing semiconducting and metallic carbon allotropes on the basis of the optimal design of band arrangements. In this chapter, we firstly introduce the photoexcitation transfer dynamics and bandgap structure limits of sc-SWCNTs in the sc-SWCNT/fullerene heterojunctions, respectively. Then, the solar cells based on all-carbon bulk and planar heterojunctions as active layers have been discussed. Finally, the recent progress about all-carbon solar cells have been highlighted, and several feasible approaches to improve the performance have also been proposed.