Excited-State Dynamics in All-Polymer Blends with Polymerized Small-Molecule Acceptors

Area of Science:

• Materials Science
• Photovoltaics
• Polymer Chemistry

Background:

• All-polymer solar cells (all-PSCs) utilize polymer acceptors for enhanced performance.
• Polymerizing small-molecular acceptors (SMAs) into polymer acceptors (PSMAs) modifies molecular packing and excited-state dynamics.
• Understanding the link between molecular packing and excited-state dynamics in PSMAs is crucial for optimizing all-PSC efficiency.

Purpose of the Study:

• To investigate the excited-state dynamics and molecular packing in polymerized SMAs (PSMAs) and their small-molecular counterparts (SMAs).
• To elucidate the relationship between molecular packing modifications and excited-state dynamics in PSMA-based all-polymer solar cells.
• To identify strategies for optimizing all-PSC performance by manipulating molecular packing and excited-state dynamics.

Main Methods:

• Experimental investigation of excited-state dynamics and molecular packing.
• Theoretical calculations to complement experimental findings.
• Comparative analysis of PSMAs and SMAs in blend systems.

Main Results:

• Charge separation is faster in blends containing PSMAs due to intra-moiety delocalized states (i-DEs).
• Looser π-π molecular packing in PSMAs suppresses excitation conversion from local excitation (LE) to i-DEs, increasing radiative losses.
• Increased PSMA aggregation reduces donor:acceptor interfaces, decreasing triplet losses from bimolecular charge recombination.

Conclusions:

• Molecular packing significantly influences excited-state dynamics in PSMAs.
• Optimizing molecular packing in PSMAs can mitigate radiative losses and reduce triplet losses.
• Tailoring molecular packing offers a pathway to enhance the performance of all-polymer solar cells.