Efficient organic solar cells with helical perylene diimide electron acceptors

Area of Science:

• Materials Science
• Photovoltaics
• Organic Electronics

Background:

• Non-fullerene acceptors are crucial for advancing organic solar cell performance.
• Solution-processed solar cells offer cost-effective manufacturing potential.
• Understanding charge dynamics at donor-acceptor interfaces is key to improving efficiency.

Purpose of the Study:

• To report the efficiency of a novel solution-processed non-fullerene solar cell.
• To investigate the photophysical processes governing charge generation and recombination.
• To explore the role of a helical perylene diimide (PDI) dimer as an electron acceptor.

Main Methods:

• Fabrication of solution-processed non-fullerene solar cells utilizing a helical PDI dimer.
• Femtosecond transient absorption spectroscopy to probe electron and hole transfer dynamics.
• Light-intensity-dependent current-voltage measurements to analyze recombination rates.

Main Results:

• Achieved a power conversion efficiency of 6.1% for the solar cell.
• Observed simultaneous electron and hole transfer at donor-acceptor interfaces.
• Demonstrated charge carrier generation from excitons in both donor and acceptor phases.
• Identified distinct recombination rates under short-circuit and open-circuit conditions.

Conclusions:

• Helical perylene diimide (PDI) dimers are effective electron acceptors in solution-processed non-fullerene solar cells.
• The study provides insights into the fundamental charge generation and recombination mechanisms.
• Further optimization of donor-acceptor morphology and energy levels could enhance device performance.