Heterojunction Interface Modification and Its Effect on the Photovoltaic Performance of Hybrid Solar Cells

Much attention has been focused on hybrid solar cells because of their low cost and high theoretical efficiencies. The photoactive layer of hybrid solar cells is composed of inorganic semiconductor and organic conjugated polymer. Excitons (electron-hole pairs) are formed upon the absorption of photons by the polymer. The excitons diffuse to the heterojunction interface between the organic donor and inorganic acceptor, and then dissociate to free electrons and holes. These electrons and holes then transfer to the inorganic and organic materials to realize charge separation and transportation. The exciton dissociation efficiency at the organic-inorganic heterojunction interface influences the photovoltaic performance of the cell. A small contact area and poor chemical compatibility between the organic and inorganic materials decrease the exciton dissociation efficiency, and thus the overall cell efficiency. This can be overcome by modifying the heterojunction interface. This paper reviews available interfacial modification methods, their function and significance, and explores prospects for the future development and application of hybrid solar cells.