Dithienoquinoxalineimide-Based Polymer Donor Enables All-Polymer Solar Cells Over 19 % Efficiency

Area of Science:

• Materials Science
• Organic Electronics
• Photovoltaics

Background:

• All-polymer solar cells (all-PSCs) offer advantages like flexibility and light weight for commercial applications.
• High-performance polymer donors are crucial for all-PSC advancement but lag behind polymer acceptors.
• Nonhalogenated materials are desirable for sustainable and cost-effective solar cell development.

Purpose of the Study:

• To design and synthesize a novel D-π-A type polymer donor (QQ1) for high-performance all-PSCs.
• To investigate the photovoltaic properties of QQ1-based all-PSCs without halogen substituents.
• To achieve record power conversion efficiencies (PCE) in all-PSCs through rational material design.

Main Methods:

• Synthesis of a new D-π-A polymer donor (QQ1) using dithienoquinoxalineimide (DTQI) and benzodithiophene (BDTT) units.
• Fabrication of all-polymer solar cells (all-PSCs) using QQ1 as the donor and PY-IT as the acceptor.
• Optimization of all-PSC performance by incorporating a third component (F-BTA3).

Main Results:

• The synthesized QQ1 polymer donor exhibits a wide band gap (1.80 eV) and deep HOMO level (-5.47 eV) without halogenation.
• QQ1-based all-PSCs achieved a power conversion efficiency (PCE) of 18.81% with a standard acceptor.
• Incorporation of F-BTA3 resulted in a record PCE of 19.20% for all-PSCs, attributed to broad absorption and reduced energy loss.

Conclusions:

• The novel nonhalogenated polymer donor QQ1 enables high-performance all-PSCs.
• Rational design of polymer donors is key to overcoming limitations in all-PSC technology.
• These findings offer insights for developing advanced nonhalogenated polymer donors for future solar energy applications.