Stable perovskite solar cells with efficiency exceeding 24.8% and 0.3-V voltage loss

Operating in wet conditions The high efficiency of the complex organic molecule Spiro-OMeTAD as a hole-transporting material for perovskite solar cells requires the use of hygroscopic dopants that decrease stability. Jeong et al. synthesized hydrophobic fluorinated analogs of Spiro-OMeTAD as hole-transporting materials that have favorable shifting of the electronic state for hole extraction and used them to fabricate perovskite solar cells. A champion device had a certified power conversion efficiency of 24.8% and an open-circuit voltage near the Shockley-Queisser limit. These devices could maintain more than 87% of the original power conversion efficiency under 50% relative humidity for more than 500 hours. Science, this issue p. 1615 Fluorinated hole-transporting layers enhance the efficiency, open-circuit voltage, and stability of perovskite solar cells. Further improvement and stabilization of perovskite solar cell (PSC) performance are essential to achieve the commercial viability of next-generation photovoltaics. Considering the benefits of fluorination to conjugated materials for energy levels, hydrophobicity, and noncovalent interactions, two fluorinated isomeric analogs of the well-known hole-transporting material (HTM) Spiro-OMeTAD are developed and used as HTMs in PSCs. The structure–property relationship induced by constitutional isomerism is investigated through experimental, atomistic, and theoretical analyses, and the fabricated PSCs feature high efficiency up to 24.82% (certified at 24.64% with 0.3-volt voltage loss), along with long-term stability in wet conditions without encapsulation (87% efficiency retention after 500 hours). We also achieve an efficiency of 22.31% in the large-area cell.