Polymer-like tetramer acceptor enables stable and 19.75% efficiency binary organic solar cells

Area of Science:

• Materials Science
• Organic Electronics
• Photovoltaics

Background:

• Current polymer acceptors in all-polymer solar cells (all-PSCs) suffer from batch inconsistencies and low polymerization, limiting device performance and stability.
• Structurally defined oligomer acceptors offer a promising alternative to overcome these limitations.

Purpose of the Study:

• To investigate the potential of a linear tetramer acceptor (4Y-BO) as a high-performance alternative to polymer acceptors in all-PSCs.
• To compare the performance and stability of devices using the tetramer acceptor (4Y-BO) with those using a control polymer acceptor (PY-BO).

Main Methods:

• Synthesis and characterization of the linear tetramer acceptor 4Y-BO.
• Fabrication of organic photovoltaic devices using PM6:4Y-BO and PM6:PY-BO blends.
• Evaluation of device performance, including power conversion efficiency (PCE), and assessment of thermal, photostability, and mechanical flexibility.

Main Results:

• The 4Y-BO acceptor exhibited refined film-forming properties, improved molecular ordering, and uniform crystallinity, leading to well-defined fibrous heterojunctions.
• PM6:4Y-BO devices achieved a power conversion efficiency of 19.75%, significantly higher than the control PM6:PY-BO devices (15.66%).
• Enhanced thermal stability, photostability, and mechanical flexibility were observed in the PM6:4Y-BO devices.

Conclusions:

• Structurally defined tetramer acceptors represent a viable strategy for advancing the performance of all-polymer solar cells.
• The 4Y-BO acceptor offers a pathway to high-efficiency, stable, and flexible organic photovoltaics.
• This work provides a new approach for fabricating high-performance and durable organic solar cells.