Seed crystals boost solvent-free perovskite solar cells to 25.53% efficiency

Engineers are exploring alternatives to silicon solar cells, with perovskites showing promise due to their efficient light absorption and potentially lower manufacturing costs. A key challenge in producing perovskite solar cells (PSCs) via vacuum deposition, a solvent-free method, has been the prevalence of performance-reducing defects in the resulting perovskite films.

Researchers at Nanjing Tech University have introduced a novel strategy to enhance vacuum deposition for PSCs. Their approach, detailed in Nature Energy, employs formamidinium acetate as a precursor material. This additive alters the chemical reaction pathway during the formation of perovskite crystals within a vacuum chamber.

This new method leads to the formation of initial "seed layers" of perovskite, guided by the reaction between formamidinium acetate and lead iodide. These seed crystals act as templates, promoting the growth of larger, more ordered perovskite crystals. Furthermore, the excess acetate helps to passivate defects that typically occur at grain boundaries, reducing energy loss.

When integrated into solar cells, these improved perovskite films achieved a power conversion efficiency (PCE) of 25.53%. The solvent-free fabrication also demonstrated excellent stability, with the devices maintaining over 95% of their initial PCE after 1,000 hours under a specific testing protocol. This development could accelerate the commercialization of high-performance perovskite photovoltaics.