High-Efficiency Solution-Processed Two-Terminal Hybrid Tandem Solar Cells Using Spectrally Matched Inorganic and Organic Photoactive Materials

Although the power conversion efficiency (PCE) of inorganic perovskite-based solar cells (PSCs) has been considerably less than that of organic-inorganic hybrid PSCs due to their wider bandgap, inorganic perovskites are great candidates for the front cell in tandem devices. Herein, we demonstrate the great potential of low-temperature solution-processed two-terminal hybrid tandem solar cell devices based on spectrally matched inorganic perovskite and organic bulk heterojunction for the front and back cells, respectively. By matching optical properties of front and back cells in the hybrid tandem device by using CsPbI2Br and PTB7-Th:IEICO-4F BHJ as the active materials, we achieved a remarkably enhanced PCE in the hybrid tandem (18.04%) as compared to that of the single-junction device (12.46% for CsPbI2Br and 11.02% for PTB7- Th:IEICO-4F). Notably, the PCE of our hybrid tandem device is thus far the highest PCE among the reported tandem devices based on perovskite and organic material. Moreover, the long-term stability of inorganic perovskite devices under stress of humidity was improved in the hybrid tandem device due to the hydrophobicity of the PTB7-Th:IEICO-4F back cell. In addition, the potential promise of this type of hybrid tandem device was calculated, where a PCE of as much as 2 ~28% is possible by improving the external quantum efficiency and reducing energy loss in the sub-cells.