Enhancing Perovskite Solar Cells Through Tailored Anchoring Groups

Self-assembled molecules (SAMs) play a crucial role as hole-selective layers in inverted perovskite solar cells, a promising next-generation solar technology. To unlock even greater efficiency and stability from these devices, scientists are exploring how different chemical 'anchoring groups' within SAMs interact with the underlying materials. This study employed advanced first-principles calculations based on density functional theory to systematically investigate eight distinct acidic anchoring groups and their effects on indium tin oxide (ITO) surfaces, a common transparent electrode.

The research uncovered significant differences in how these anchoring groups behave. Silicic acid, cyanoacetic acid, cyanophosphoric acid, and phosphoric acid emerged as the strongest in terms of absorption ability, with a clear correlation: increasing the number of dehydrogenations in an anchoring group boosts the SAM's overall adsorption capacity. Beyond just absorption, the study found that the adsorption of SAMs can cause a change in ITO's work function, presenting a potential strategy to modify the work function of transparent conductive oxide substrate by anchoring group engineering. Furthermore, high-temperature simulations revealed that silicic acid and phosphoric acid anchoring groups have the best thermal stability, a critical factor for long-lasting solar cells.

Delving deeper into the interface between SAMs and the perovskite material (SAMs/FAPbI3), the cyanoacetic acid anchoring group demonstrated the largest adsorption energy, indicating a strong and stable interaction. These detailed insights provide a roadmap for material scientists, highlighting how the deliberate design of anchoring groups can profoundly influence the performance and durability of perovskite solar cells. As lead author Liu notes in the paper, "This work shows the great potential of precisely designed self-assembled molecules for high-performance perovskite solar cells."