As renewable energy takes center stage in global efforts to combat climate change, advancements in solar technology continue to play a vital role. Among these developments, tandem solar cells (TSCs), particularly all-perovskite versions, offer exciting potential owing to their ability to optimize light absorption across various wavelengths, potentially exceeding traditional solar cell efficiencies. However, realizing their full potential has often been stymied by technical challenges, particularly those concerning mismatched crystallization between the wide-bandgap (WBG) and narrow-bandgap (NBG) subcells.
In a remarkable breakthrough, scientists at the Ningbo Institute of Materials Technology and Engineering have achieved a power conversion efficiency (PCE) of 29.76% in all-perovskite TSCs. This success, documented in the journal Joule, employs a novel unified colloidal chemistry approach. This technique involves a carboxylate-based modulator system that precisely controls the nucleation dynamics of the subcells using tartrate (Ta-) and citrate (Cit-) anions.
The Ta- anions play a pivotal role in the WBG subcell by stabilizing lead ions (Pb2+), thereby preventing phase segregation and promoting uniform crystallization. Simultaneously, Cit- anions enhance tin-iodine bonding in the NBG colloids, mitigating Sn2+ defects to improve charge transport efficiency. Additionally, the use of choline cations to passivate undercoordinated metal ions at crystal interfaces further stabilizes the cell structure.
This innovative approach not only achieved a commendable PCE but also demonstrated exceptional operational stability, maintaining more than 90.2% of its initial efficiency after 700 hours of continuous operation under maximum power point tracking conditions. The researchers further showcased the method’s scalability by achieving high efficiency in large-area (1 cm²) tandem cells.
Key Takeaways:
The achievements of the team at the Chinese Academy of Sciences mark a significant advancement in solar technology. By addressing crystallization challenges through advanced colloidal chemistry, the researchers have opened new avenues for the development of stable, efficient, and scalable solar cells. Such strides in solar efficiency are pivotal for the future commercialization of high-efficiency solar technologies, underscoring the growing role of renewables in shaping a sustainable energy future.