Enhancing D/A Interactions via Porphyrin Isomerization to Improve Photovoltaic Performance

Area of Science:

• Materials Science
• Organic Electronics
• Photovoltaics

Background:

• Donor/acceptor (D/A) interactions are crucial for organic solar cell (OSC) performance.
• The influence of isomerism on D/A interactions within OSCs remains underexplored.
• Molecular geometry and property optimization via isomerization can enhance device efficiency.

Purpose of the Study:

• To investigate the impact of donor isomerism on D/A interactions in OSCs.
• To synthesize and characterize two small molecule donors, m-ph-ZnP2 and p-ph-ZnP2, differing in phenyl linkage positions.
• To correlate structural modifications with photovoltaic performance.

Main Methods:

• Synthesis of meta- and para-linked porphyrin-based small molecule donors (m-ph-ZnP2 and p-ph-ZnP2).
• Fabrication and characterization of binary OSCs using synthesized donors and PC61BM.
• Fabrication and characterization of ternary OSCs incorporating m-ph-ZnP2, Y6, and PC61BM.
• Analysis of D/A interactions, charge transfer, and recombination dynamics.

Main Results:

• m-ph-ZnP2 exhibited reduced self-aggregation and enhanced interactions with PC61BM compared to p-ph-ZnP2.
• Binary OSCs based on m-ph-ZnP2 achieved a power conversion efficiency (PCE) of 5.43%, significantly higher than the 2.03% for p-ph-ZnP2 devices.
• Enhanced performance in m-ph-ZnP2 devices is attributed to stronger intramolecular charge transfer (ICT), improved D/A interactions, and suppressed charge recombination.
• Ternary devices (m-ph-ZnP2:Y6:PC61BM) reached a PCE of 8.34%.

Conclusions:

• Donor isomerism is a critical factor in tuning D/A interactions and optimizing OSC performance.
• The meta-linkage in m-ph-ZnP2 promotes superior D/A interactions, leading to higher PCE.
• This study provides valuable insights for designing efficient small molecule donors for organic solar cells.