Constructing High-Performance Solar Cells by Incorporating an A1-A2-Type Polymer Donor as a Guest Material

Area of Science:

• Materials Science
• Organic Electronics
• Photovoltaics

Background:

• Donor-Acceptor (D-A) polymer donors are crucial for high-performance organic solar cells.
• However, D-A polymers suffer from high voltage loss due to imperfect energy levels.
• Developing new polymer architectures is essential to mitigate these limitations.

Purpose of the Study:

• To design and synthesize a novel A1-A2 type copolymer, M1, to address energy level mismatches in polymer solar cells.
• To investigate the impact of M1 as a guest material in ternary blend systems.
• To enhance the power conversion efficiency (PCE) and photostability of organic photovoltaic devices.

Main Methods:

• Synthesis of an A1-A2 type copolymer (M1) using BDD as the A1 unit and DTBT as the A2 unit.
• Fabrication of ternary blend organic solar cells incorporating M1 into a PM6:L8-BO system.
• Characterization of film morphology, molecular orientation, energy levels, and device performance.

Main Results:

• The A1-A2 type polymer M1 exhibited lower energy levels, broader absorption, and enhanced crystallinity compared to D-A type polymer PM6.
• Ternary blend films with M1 showed improved face-on molecular orientation and active-layer morphology.
• The optimized ternary device (PM6:M1(5%):L8-BO) achieved a high PCE of 19.70% and superior photostability.

Conclusions:

• The novel A1-A2 type polymer M1 effectively reduces voltage loss and enhances device performance in organic solar cells.
• Introducing M1 as a guest material in ternary blends offers a promising strategy for high-performance organic photovoltaics.
• This work presents an efficient approach to developing advanced ternary devices with improved efficiency and stability.