Achieving 12.8% Efficiency by Simultaneously Improving Open‐Circuit Voltage and Short‐Circuit Current Density in Tandem Organic Solar Cells

Tandem organic solar cells (TOSCs), which integrate multiple organic photovoltaic layers with complementary absorption in series, have been proved to be a strong contender in organic photovoltaic depending on their advantages in harvesting a greater part of the solar spectrum and more efficient photon utilization than traditional single‐junction organic solar cells. However, simultaneously improving open circuit voltage (Voc) and short current density (Jsc) is a still particularly tricky issue for highly efficient TOSCs. In this work, by employing the low‐bandgap nonfullerene acceptor, IEICO, into the rear cell to extend absorption, and meanwhile introducing PBDD4T‐2F into the front cell for improving Voc, an impressive efficiency of 12.8% has been achieved in well‐designed TOSC. This result is also one of the highest efficiencies reported in state‐of‐the‐art organic solar cells.