Electrostatic Potential Complementarity for Thickness-Tolerant Cathode Interlayers in High-Efficiency Organic and...

Area of Science:

• Materials Science
• Organic Electronics
• Photovoltaics

Background:

• Designing cathode interlayers (CILs) for organic solar cells (OSCs) faces challenges in achieving high efficiency, stability, and thickness tolerance.
• Understanding intermolecular interactions within CILs is crucial for optimizing device performance.

Purpose of the Study:

• To elucidate the molecular origin of thickness sensitivity in CILs for OSCs.
• To develop an electrostatic potential (ESP) guided strategy for engineering high-performance CILs.
• To investigate the impact of small molecules with opposite ESP distributions on CIL properties.

Main Methods:

• Systematic study of trimesic acid (TMA) and phloroglucinol (PG) as model CIL components.
• Analysis of intermolecular interactions between PG and the benchmark CIL material PDINN.
• Fabrication and characterization of OSCs and perovskite-organic tandem solar cells (TSCs) using the engineered CILs.

Main Results:

• PG incorporation enhanced PDINN self-doping, conductivity, energy-level alignment, and π-π stacking.
• The PDINN:PG CIL improved charge extraction, transport, and suppressed recombination losses.
• OSCs achieved a 20.0% power conversion efficiency (PCE) with excellent thickness tolerance (87.0% at 50 nm) and stability (80% after 600 h).
• Perovskite-organic TSCs reached a PCE of 26.4%.

Conclusions:

• Complementary ESP matching between PG and PDINN is key to superior CIL performance.
• The ESP-guided molecular interfacial engineering strategy enables thickness-tolerant and durable CILs for next-generation solar cells.
• This approach offers a pathway for advancing OSC and TSC technologies.