Morphology Control for Efficient Nonfused Acceptor-Based Organic Photovoltaic Cells

Area of Science:

• Materials Science
• Organic Electronics
• Photovoltaics

Background:

• Non-fused electron acceptors offer cost advantages for organic photovoltaic (OPV) cells.
• Controlling blend morphology is challenging due to molecular flexibility in non-fused acceptors.
• Understanding donor-acceptor interactions is crucial for optimizing OPV performance.

Purpose of the Study:

• To investigate the impact of polymer donor selection on blend morphology in non-fused acceptor-based OPV cells.
• To correlate blend morphology with device performance, specifically power conversion efficiency (PCE) and fill factor (FF).
• To design and evaluate a novel selenium-containing non-fused acceptor (ASe-5).

Main Methods:

• Fabrication of OPV devices using two polymer donors (PBDB-TF, PBQx-TF) and a non-fused acceptor (ASe-5).
• Morphological analysis of blend films to assess miscibility and phase separation.
• Device characterization to measure PCE, FF, charge transfer, and recombination dynamics.

Main Results:

• PBQx-TF exhibited lower miscibility with ASe-5 compared to PBDB-TF, leading to more pronounced phase separation.
• The PBQx-TF:ASe-5 blend showed enhanced preaggregation and earlier polymer network formation.
• PBQx-TF:ASe-5 devices achieved a higher PCE of 14.7% and FF of 0.744 due to faster charge transfer and suppressed recombination.

Conclusions:

• Donor selection significantly influences blend morphology and OPV device performance.
• PBQx-TF is a more suitable donor for the ASe-5 acceptor, resulting in superior device efficiency.
• Optimizing morphology through strategic donor selection is vital for advancing non-fused acceptor-based OPV technology.