Tailoring and Modifying an Organic Electron Acceptor toward the Cathode Interlayer for Highly Efficient Organic Solar...

Area of Science:

• Organic electronics
• Materials science
• Photovoltaics

Background:

• Organic solar cells (OSCs) require optimized electrode interlayers to match evolving active layer materials.
• Traditional interlayers often limit the efficiency of new OSC active layers.
• Advancements in OSC materials necessitate novel interlayer designs for improved performance.

Purpose of the Study:

• To develop a new cathode interlayer (CIL) material for high-performance organic solar cells (OSCs).
• To investigate the role of CIL molecular design, specifically the end-capping unit, in enhancing OSC power conversion efficiency (PCE).
• To explore the impact of electrostatic potential difference at the CIL/active layer interface on exciton dissociation and charge generation.

Main Methods:

• Design and synthesis of a new CIL molecule (S-3) by tailoring the ITIC end-capping unit.
• Fabrication and characterization of OSC devices incorporating the novel S-3 CIL.
• Utilizing density functional theory (DFT) calculations to predict the influence of CIL chemical structure on exciton dissociation.

Main Results:

• The S-3 molecule demonstrated excellent electron accepting capacity, suitable energy levels, and good film-forming properties for efficient electron extraction.
• OSC devices utilizing the S-3 CIL achieved a high power conversion efficiency (PCE) of 16.6%.
• A significant correlation was found between the electrostatic potential difference of the CIL and enhanced exciton dissociation, leading to increased current density.

Conclusions:

• A novel design strategy for high-performance CILs in OSCs was successfully demonstrated.
• The S-3 molecule represents a promising CIL material for achieving high PCE in organic solar cells.
• DFT calculations provide a reliable method for predicting CIL performance and guiding future material design for improved exciton dissociation.