Grain Boundary Chemical Anchoring via Bidirectional Active Site Additive Enables Efficient and Stable Perovskite Solar Cells

The nonradiative recombination induced by trap states at the surface and grain boundaries impedes the further increase of power conversion efficiency (PCE) and stability of perovskite solar cells (PSCs). Consequently, it is highly desirable to minimize the trap-assisted nonradiative recombination in perovskite films. Here, an effective additive engineering strategy is reported where N-succinimidyl 6-maleimidohexanoate (denoted as NSMH) with multiple active sites and hydrophobic alkyl chains were incorporated for fully eliminating undercoordinated Pb2+ traps in perovskite films. It is revealed that improved crystallinity and reduced defect density are achieved, which is ascribed to the strong coordination interaction between the carbonyl groups at both sides of NSMH molecules and Pb2+. As a result, the NSMH-modified device exhibits a champion PCE of 22.40% with negligible hysteresis, which is significantly higher than 20.67% of the control device. The unencapsulated modified device exhibits no degradation while the control device degrades to 82% of its initial PCE after storing for 1536 h in a relative humidity of 10-20% at room temperature in the dark.

Automated summary

By utilizing the NSMH additive engineering strategy, the trap-assisted nonradiative recombination in perovskite films is effectively minimized, leading to improved crystallinity and reduced defect density. As a result, the NSMH-modified perovskite solar cell exhibits a significantly higher power conversion efficiency and stability compared to the control device.