Semiconducting Covalent Organic Frameworks as Functional Dopants for Efficient Perovskite Solar Cells

Why It Matters

Effective bulk doping addresses two critical bottlenecks—defect‑induced recombination and charge transport—thereby accelerating the commercial viability of perovskite solar technology.

Key Takeaways

• PyCOFs act as bulk dopants in FAPbI3 PSCs
• Lewis-basic groups passivate Pb2+ trap sites
• π‑conjugated linkages boost charge transport
• Champion efficiency reaches ~19.5% versus 17.75% baseline
• Design offers stable, tunable perovskite photovoltaics

Pulse Analysis

Perovskite solar cells have surged ahead of traditional silicon due to their high absorption coefficients and low‑temperature processing, yet widespread adoption remains hampered by defect‑mediated non‑radiative recombination and long‑term instability. Researchers have long pursued surface passivation layers, but bulk strategies that simultaneously enhance charge mobility are rarer. Introducing functional dopants that integrate seamlessly into the perovskite matrix can address both issues, offering a pathway to retain the material’s intrinsic optoelectronic advantages while mitigating its weaknesses.

Covalent organic frameworks (COFs) provide a uniquely modular platform for such bulk doping. By selecting pyrene cores and tailoring linkages—sp2‑carbon, imine, or thiol groups—the resulting PyCOFs present extended π‑conjugation for efficient charge delocalization and Lewis‑basic sites that bind undercoordinated Pb2+ ions. This dual functionality not only neutralizes deep trap states but also creates conductive pathways within the perovskite bulk, a combination rarely achieved with conventional additives. The study’s systematic comparison of three PyCOF chemistries underscores how subtle changes in functional groups translate directly into defect passivation efficacy and carrier transport.

Performance data validate the concept: PyCOF‑doped devices achieve a champion efficiency of roughly 19.5%, a notable jump from the 17.75% baseline and outperforming pyrene‑free COF controls. Higher fill factors and reduced hysteresis indicate more efficient charge extraction, while the unchanged crystal structure suggests that the dopants do not compromise material stability. For the solar industry, this represents a scalable, chemistry‑driven route to bridge the gap between laboratory efficiencies and reliable, long‑lasting modules, positioning perovskite technology closer to large‑scale deployment. Future work will likely explore further functional group diversification and integration with encapsulation strategies to cement perovskite cells as a mainstream renewable energy solution.