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

Area of Science:

• Materials Science
• Renewable Energy
• Photovoltaics

Background:

• Perovskite solar cells (PSCs) show great promise but suffer from efficiency limitations due to defects.
• Formamidinium lead iodide (FAPbI3) is a key perovskite material for PSCs.
• Covalent organic frameworks (COFs) offer tunable properties for materials applications.

Purpose of the Study:

• To investigate pyrene-based COFs as bulk dopants in FAPbI3 PSCs.
• To evaluate the impact of COF linkage chemistry and functionalities on PSC performance.
• To establish a molecular design platform for high-performance perovskite photovoltaics.

Main Methods:

• Synthesis of three pyrene-based COFs (sp2c-PyCOF, Im-PyCOF, SH-PyCOF) with varying functionalities.
• Incorporation of PyCOFs as bulk dopants into FAPbI3 perovskite precursor solutions.
• Characterization of optoelectronic properties and device performance of doped and undoped PSCs.

Main Results:

• PyCOFs effectively passivate deep trap states in FAPbI3 by coordinating with Pb2+ sites.
• Extended π-conjugation in PyCOFs facilitates charge delocalization and transfer.
• PyCOF-doped PSCs exhibited enhanced charge extraction and Fill Factors, reaching a champion efficiency of ~19.5%.

Conclusions:

• Pyrene-based COFs are effective multifunctional dopants for FAPbI3 PSCs.
• These COFs improve perovskite stability and optoelectronic performance.
• The study presents a rational design strategy for next-generation perovskite solar cells.