Electron Transport Improvement of Perovskite Solar Cells via a ZIF-8-Derived Porous Carbon Skeleton

To improve electron transport rate of perovskite solar cells, a ZIF-8-derived porous carbon skeleton layer is prepared by carbonizing the ZIF-8 thin film on conducting glass as the electron transport skeleton of a perovskite solar cell. Polyvinylpyrrolidone is added during the synthesis of ZIF-8 to reduce the particle size of ZIF-8 and decrease the carbonization temperature below 600 °C. The porous structure of ZIF-8 is mainly reserved at the optimized carbonization temperature. Then, TiO₂ nanoparticles are deposited on the surface of a porous carbon skeleton to form an electron transport layer of a perovskite solar cell with the structure of FTO/ZIF-8-derived porous carbon layer/TiO₂/perovskite/spiro-OMeTAD/Au. Because of the good conductivity of the ZIF-8-derived porous carbon skeleton, the photogenerated electron transport rate of the perovskite solar cell is increased. At the same time, the porous structure of the ZIF-8-derived carbon layer increases the contact area between the perovskite layer and the TiO₂ layer to favor separation of photogenerated charges. Therefore, the light-to-electric conversion efficiency of the CH₃NH₃PbI₃ perovskite solar cell is enhanced from 14.25% to 17.32%.