Correlating Charge Transfer Dynamics with Interfacial Trap States in High-Efficiency Organic Solar Cells.

Area of Science:

• Materials Science
• Organic Electronics
• Photovoltaics

Background:

• Charge transfer dynamics at donor/acceptor interfaces are crucial for organic solar cell performance.
• The role of high-density traps at these interfaces in charge transfer remains incompletely understood.

Purpose of the Study:

• To establish a general correlation between trap densities and charge transfer dynamics in organic solar cells.
• To elucidate the impact of interfacial traps on electron and hole transfer rates.
• To provide insights into optimizing organic heterostructures for enhanced photovoltaic performance.

Main Methods:

• Investigated a series of high-efficiency organic photovoltaic blends.
• Analyzed charge transfer rates in relation to varying trap densities.
• Correlated interfacial trap characteristics with device efficiency.

Main Results:

• Electron transfer rates decrease significantly with increasing trap densities due to induced potential barriers.
• Hole transfer rates remain independent of trap states, driven by sufficient thermal energy.
• Achieved a power conversion efficiency of 17.18% in devices with minimized interfacial trap densities (PM6:BTP-eC9).

Conclusions:

• Interfacial trap density critically influences charge transfer dynamics, particularly electron transfer, in organic solar cells.
• Understanding and mitigating traps is essential for improving the efficiency of organic photovoltaic devices.
• This study offers fundamental insights into charge transfer mechanisms at non-ideal interfaces in organic heterostructures.