WO Nanoparticles or Nanorods Incorporating CsCO/PCBM Buffer Bilayer as Carriers Transporting Materials for Perovskite Solar Cells.

In this work, we demonstrate a novel carrier transporting combination made of tungsten trioxide (WO) nanomaterials and CsCO/PCBM buffer bilayer for the fabrication of perovskite solar cells (PSCs). Two different types of WO, including nanoparticles and nanorods, were prepared by sol-gel process and hydrothermal method, respectively. CsCO/PCBM buffer bilayer was inserted between WO and perovskite layers to improve charge transfer efficiency and formation of pinhole-free perovskite layer. Besides, the leakage current of the devices containing CsCO/PCBM buffer bilayer was significantly suppressed. The optimized device based on WO nanoparticles and CsCO/PCBM bilayer showed an open-circuit voltage of 0.84 V, a short-circuit current density of 20.40 mA/cm, a fill factor of 0.61, and a power conversion efficiency of 10.49 %, which were significantly higher than those of PSCs without CsCO/PCBM buffer bilayer. The results revealed that the combination of WO nanomaterials and CsCO/PCBM bilayer provides an effective solution for improving performances of PSCs.