Mixed-Isomers Strategy for Thermally Stable and High-Performance Thick-Film All-Small-Molecule Organic Solar Cells

Area of Science:

• Materials Science
• Organic Electronics
• Photovoltaics

Background:

• All-small-molecule organic solar cells (all-SMOSCs) offer advantages like tunability and consistency.
• Current all-SMOSCs lag behind polymer-based solar cells (PSCs) in power conversion efficiency (PCE) due to charge management and morphology issues.

Purpose of the Study:

• To improve the performance of all-SMOSCs by addressing charge management and morphology control.
• To develop a quaternary blend system for enhanced photovoltaic properties.

Main Methods:

• Incorporation of two complementary isomers (BTP-Br-γ and BTP-Br-δ) into a host system (MPhS-C2:BTP-eC9) to create quaternary blends.
• Device fabrication and characterization to evaluate photovoltaic performance.

Main Results:

• The optimized quaternary blend solar cell achieved a record power conversion efficiency (PCE) of 19.06% (certified 18.7%).
• Demonstrated superior morphological robustness, efficient charge transport, and suppressed energy loss.
• Exhibited high thickness tolerance, device efficiency, and thermal stability.

Conclusions:

• The developed quaternary system offers a viable strategy to enhance all-SMOSC performance.
• This advancement helps bridge the efficiency gap between all-SMOSCs and PSCs.
• Paves the way for practical applications of high-efficiency organic photovoltaics.