Halogenated diphenyl ether solvent additives enable ∼20% efficiency organic solar cells and high-performance...

Area of Science:

• Materials Science
• Organic Electronics
• Photovoltaics

Background:

• Solvent additives are crucial for optimizing the morphology of organic solar cells (OSCs).
• Tuning active layer morphology directly impacts power conversion efficiency (PCE).

Purpose of the Study:

• To develop novel halogenated diphenyl ether (DPE) solvent additives for OSCs.
• To investigate the effect of halogenation on DPE additives and their impact on active layer morphology and device performance.

Main Methods:

• Synthesis of three DPE additives: DPE-F, DPE-Cl, and DPE-Br.
• Fabrication of OSCs using PM6:L8-BO as the active layer with DPE additives.
• Characterization of additive properties (boiling point, dipole moment) and their influence on film morphology, charge transport, and device performance.

Main Results:

• DPE additives exhibited increasing boiling points and dipole moments with increasing halogen atomic weight.
• DPE-Br demonstrated enhanced non-covalent interactions, leading to improved intermolecular packing and charge transport.
• DPE-Br-treated OSCs achieved a PCE of 18.40%, outperforming DPE-F (17.73%) and DPE-Cl (18.03%).
• OSCs utilizing D18:L8-BO:BTP-eC9 with DPE-Br achieved PCEs of ~20%.
• Opaque and semitransparent modules achieved high PCEs of 16.42% and 10.50%, respectively.

Conclusions:

• Halogenation of DPE-derived additives is an effective strategy for optimizing OSC morphology.
• The DPE-Br additive significantly enhances OSC performance and module efficiency.
• This approach offers a promising route for developing highly efficient organic solar cells and modules.