A Multifunctional 2D-Conjugated BDT Polymer Interlayer Enables Over 20% Organic Solar Cells

Area of Science:

• Materials Science
• Organic Electronics
• Photovoltaics

Background:

• The morphology of the active layer in organic solar cells (OSCs) critically impacts charge transport and recombination.
• Conventional bulk heterojunction (BHJ) methods often lead to poor vertical phase distribution, limiting power conversion efficiency (PCE).

Purpose of the Study:

• To design a novel 2D conjugated polymer donor, PBDB-tvt, with enhanced properties for OSCs.
• To investigate the effect of a multifunctional interlayer on active layer morphology and photovoltaic performance.

Main Methods:

• Synthesized a 2D conjugated polymer donor (PBDB-tvt) with a benzodithiophene (BDT) core and a chlorinated alkylthio-thiophene-vinyl-thiophene (tvt) side chain.
• Utilized PBDB-tvt as an interlayer in a hybrid device configuration (functional modification layer/BHJ) for sequential deposition.
• Analyzed the impact of the tailored structure on phase distribution, light utilization, and photovoltaic parameters.

Main Results:

• The PBDB-tvt polymer exhibited up-shifted energy levels, enhanced optical absorption, and improved charge transport.
• The hybrid device configuration with the PBDB-tvt interlayer showed improved phase distribution and enhanced short-wavelength light utilization.
• Key photovoltaic parameters, including open-circuit voltage, short-circuit current density, and fill factor, were simultaneously increased.

Conclusions:

• The designed multifunctional interlayer plays a crucial role in optimizing active layer morphology and enhancing light absorption in OSCs.
• The novel PBDB-tvt polymer and hybrid device architecture offer a viable strategy for significantly improving OSC performance.
• A record PCE of 20.3% was achieved, demonstrating the potential of this approach for advancing organic solar cell technology.