Miscibility Tuning for Optimizing Phase Separation and Vertical Distribution toward Highly Efficient Organic Solar...

Area of Science:

• Materials Science
• Organic Electronics
• Photovoltaics

Background:

• Ternary organic materials enhance power conversion efficiency in organic solar cells (OSCs).
• Optimizing morphology and miscibility is crucial for efficient charge separation, transport, and collection.

Purpose of the Study:

• To investigate the effect of DRCN5T as a third component in PTB7-Th:PC70BM based OSCs.
• To understand how DRCN5T influences blend film morphology and miscibility for improved device performance.

Main Methods:

• Fabrication of large-area OSCs with blend film thickness up to 270 nm.
• Characterization of film morphology, including π-π stacking and domain purity.
• Quantitative analysis of component miscibility using the Flory-Huggins interaction parameter.

Main Results:

• Inclusion of DRCN5T in PTB7-Th:PC70BM systems resulted in OSCs achieving 11.1% power conversion efficiency.
• DRCN5T addition formed an interconnected fibrous network, decreased π-π stacking, and enhanced domain purity.
• Optimized vertical distribution of PTB7-Th and PC70BM led to improved charge separation, transport, and collection.
• Flory-Huggins parameters indicated specific miscibility interactions: -0.80 for DRCN5T:PTB7-Th and 2.94 for DRCN5T:PC70BM.

Conclusions:

• DRCN5T effectively optimizes morphology and miscibility in ternary OSCs, leading to significant performance enhancement.
• The findings provide guidance for selecting third additives to achieve high-performance, large-area OSCs suitable for printing and roll-to-roll fabrication.