Core–Shell ZnO@SnO2 Nanoparticles for Efficient Inorganic Perovskite Solar Cells

The ideal charge transport materials should exhibit a proper energy level, high carrier mobility, sufficient conductivity, and excellent charge extraction ability. Here, a novel electron transport material was designed and synthesized by using a simple and facile solvothermal method, which is composed of the core–shell ZnO@SnO2 nanoparticles. Thanks to the good match between the energy level of the SnO2 shell and the high electron mobility of the core ZnO nanoparticles, the PCE of inorganic perovskite solar cells has reached 14.35% (JSC: 16.45 mA cm–2, VOC: 1.11 V, FF: 79%), acting core–shell ZnO@SnO2 nanoparticles as the electron transfer layer. The core–shell ZnO@SnO2 nanoparticles size is 8.1 nm with the SnO2 shell thickness of 3.4 nm, and the electron mobility is seven times more than SnO2 nanoparticles. Meanwhile, the uniform core–shell ZnO@SnO2 nanoparticles is extremely favorable to the growth of inorganic perovskite films. These preliminary results strongly suggest the great potential of this novel electron transfer material in high-efficiency perovskite solar cells.