Quinacridone-based molecular donors for solution processed bulk-heterojunction organic solar cells

Area of Science:

• Materials Science
• Organic Electronics
• Photovoltaics

Background:

• Organic solar cells (OSCs) require efficient electron donor materials for solution processing.
• Quinacridone pigments offer a promising core structure but often lack solubility.
• Developing soluble, high-performance donor materials is crucial for advancing OSC technology.

Purpose of the Study:

• To synthesize and characterize novel soluble quinacridone-based molecules as electron donors for OSCs.
• To investigate the structure-property relationships influencing optical and electrochemical characteristics.
• To evaluate the performance of these materials in bulk heterojunction (BHJ) solar cells.

Main Methods:

• Functionalization of quinacridone with alkyl chains and thiophene units (bithiophene and thienylbenzo[c][1,2,5]thiadiazolethienyl).
• Spectroscopic (absorption) and electrochemical (cyclic voltammetry) characterization.
• Fabrication and testing of BHJ OSCs using the synthesized molecules and PC70BM acceptor.

Main Results:

• Synthesized multifunctional quinacridone derivatives (QA, QA-BT, QA-BTD) with tunable visible light absorption.
• Observed extended absorption edges with increased molecular conjugation (up to 637 nm).
• Achieved power conversion efficiencies (PCEs) up to 2.22% and external quantum efficiencies (EQEs) up to ~45% in BHJ OSCs.

Conclusions:

• Soluble quinacridone-based molecules are effective electron donors for solution-processed OSCs.
• Molecular design allows tuning of optical and electrochemical properties for enhanced performance.
• These materials represent a promising advancement for efficient and cost-effective organic photovoltaics.