17.68% Efficiency Nonhalogenated Solvent-Processed Organic Solar Cell Modules Driven by Seed Crystal Strategy

Area of Science:

• Materials Science
• Organic Electronics
• Renewable Energy

Background:

• Organic solar cells (OSCs) achieve high efficiencies but face scalability challenges due to toxic solvents like chloroform.
• Alternative high-boiling, non-halogenated solvents present issues with solubility and crystallization.
• Optimizing film formation and crystallization is crucial for industrial OSC production.

Purpose of the Study:

• To introduce a seed crystal strategy for improved nucleation and crystallization in organic solar cells.
• To develop a method for enhancing the performance of large-area organic solar cell modules.
• To overcome the limitations of traditional solvents and processing methods.

Main Methods:

• Incorporation of oligo(ethylene glycol)-modified small-molecule donors as seed crystals.
• Utilizing an asymmetric BDTF-CA2O molecule to promote polymer donor (PM6) crystallization.
• Optimizing film morphology, including phase separation and vertical distribution.

Main Results:

• The seed crystal strategy significantly improved the crystallization of the polymer donor PM6.
• BDTF-CA2O suppressed excessive phase separation and optimized film vertical distribution.
• Small-area devices processed with toluene achieved 19.67% power conversion efficiency.
• Large-area organic solar cell modules reached a record active area efficiency of 17.68% and aperture area efficiency of 16.80% (>10 cm²).

Conclusions:

• The seed crystal strategy is effective in optimizing nucleation and crystallization for organic solar cells.
• This approach enhances exciton extraction, carrier transport, and reduces recombination losses.
• The study demonstrates a viable pathway for the large-scale production of efficient, large-area organic solar cell modules.