Bifunctional thiourea-based additives for synergistic enhancement of perovskite crystallization and defect density...

Hybrid perovskite solar cells (PSCs) have emerged as a promising alternative to crystalline silicon solar cells, owing to their excellent photovoltaic characteristics and straightforward fabrication processes. However, the rapid crystallization dynamics frequently results in unfavorable film morphology, giving rise to a plethora of defect sites and fostering the formation of trapped non-radiative recombination centers, thus limiting the further advancement and refinement of PSC technology. In this study, we introduce N-benzoylthiourea (N-BzTu) molecules as a passivate agent within PSCs through anti-solvent additive approach. The incorporation of CO and CS functional groups in N-BzTu effectively passivates the under-coordinated Pb²⁺ defects, while the formation of robust hydrogen bonding interactions between NH or NH₂ groups and I^- ions acts as a potent inhibitor against the generation of iodine vacancy defects. This dual-action mechanism not only addresses the issue of defect proliferation but also enhances the overall structural integrity of the PSC film. Moreover, by meticulously adjusting the growth rate of the perovskite crystals, we can achieve dense and uniformly distributed perovskite films. Specifically, the power conversion efficiency (PCE) of the optimized devices soared from 22.11 % to an impressive 24.05 %. Consequently, the hydrothermal stability of the device is also improved, with the initial efficiency of the unencapsulated device remaining above 80 % after 1540 h at 20-25 % relative humidity.