Asymmetric Small Molecule as Interface Governor for FAPbI3 Perovskite Solar Cells

Delicate interface modification is necessary for improving the photovoltaic performance of a perovskite solar cell (PSC). Herein, two asymmetric small molecules, termed BTD-DA and BTD-PA are designed and synthesized to govern the perovskite/Spiro-OMeTAD interface. The molecule BTD-PA featuring a donor-acceptor-acceptor (D-A-A ') configuration shows a larger molecule dipole and a better effect on defect passivation and energy level regulation through the strong interaction between the pyridine group in BTD-PA and the surficial uncoordinated Pb2+. Consequently, the PSCs based on the BTD-PA treatment harvest a champion power conversion efficiency (PCE) of 24.46% for a 0.09 cm(2) active area and 22.46% for the 1 cm(2) device. Moreover, the long-term stability of FAPbI(3) PSCs is also significantly improved because of the enhanced hydrophobicity and the inhibited phase transition of the FAPbI(3) film with BTD-PA treatment. Our research provides a new strategy for interfacial engineering to boost the PCE and stability of the FAPbI(3) PSCs.

Automated summary

In this study, two asymmetric small molecules, BTD-DA and BTD-PA, were designed and synthesized to modify the perovskite/Spiro-OMeTAD interface in order to improve the photovoltaic performance of perovskite solar cells (PSCs). The molecule BTD-PA showed better defect passivation and energy level regulation due to its strong interaction with the uncoordinated Pb2+ on the perovskite surface. PSCs treated with BTD-PA achieved a champion power conversion efficiency of 24.46% and 22.46% for different active areas, and showed improved long-term stability.