Introducing 4-Methoxythiophene Side Chains into β-Functionalized Porphyrins to Enhance Their Photovoltaic Performance

Area of Science:

• Materials Science
• Organic Electronics
• Photovoltaics

Background:

• Meso-substituted porphyrins are widely studied for organic solar cells (OSCs).
• β-substituted porphyrins remain less explored despite their potential.
• Previous work showed β-functionalized porphyrins can achieve 6.96% power conversion efficiency (PCE).

Purpose of the Study:

• To investigate the impact of side-chain engineering on β-substituted porphyrin performance in OSCs.
• To synthesize and evaluate novel small molecular donors based on β-diketopyrrolopyrrole (DPP) porphyrins with 4-methoxythiophene side chains.
• To optimize blend morphology for enhanced charge transport and reduced recombination.

Main Methods:

• Synthesis of two small molecular donors: 4β-DPP-MOT(EH)-Por and 4β-DPP-MOT(HD)-Por, featuring DPP units at β-positions and 4-methoxythiophene side chains at meso-positions.
• Fabrication and characterization of OSC devices using these novel porphyrin donors blended with the Y6 acceptor.
• Analysis of blend film morphology, intermolecular interactions, charge transport, and recombination dynamics.

Main Results:

• The introduction of 4-methoxythiophene side chains enhanced intermolecular interactions compared to alkyl side chains.
• The 4β-DPP-MOT(EH)-Por:Y6 blend exhibited superior morphology, facilitating efficient charge transport and suppressing recombination.
• The champion PCE reached 9.18% for 4β-DPP-MOT(EH)-Por:Y6 based OSCs, significantly outperforming the 4β-DPP-MOT(HD)-Por:Y6 device (8.14% PCE).

Conclusions:

• Side-chain engineering of β-substituted porphyrins is a viable strategy for developing high-performance small-molecule donor materials.
• Optimizing blend morphology through strategic side-chain design is crucial for improving OSC efficiency.
• The synthesized 4β-DPP-MOT(EH)-Por shows significant potential for future OSC applications.