Robust singlet fission process in strong absorption π-expanded diketopyrrolopyrroles

Area of Science:

• Materials Science
• Photovoltaics
• Organic Electronics

Background:

• Singlet fission (SF) is a promising process for enhancing solar cell efficiency by generating multiple excitons from a single photon.
• Current SF-based solar cells are limited by the scarcity of efficient and stable SF materials, hindering practical applications.
• Developing novel SF chromophores is crucial for overcoming efficiency limitations and reducing thermal losses in solar energy conversion.

Purpose of the Study:

• To design and synthesize new singlet fission (SF) chromophores based on polycyclic diketopyrrolopyrrole (DPP) derivatives.
• To investigate the photophysical properties and intermolecular packing of these novel Ex-DPPs for efficient SF.
• To establish design guidelines for developing high-performance SF materials for practical light-harvesting applications.

Main Methods:

• A π-expansion strategy was employed to synthesize a new series of robust SF chromophores, termed Ex-DPPs.
• Characterization of Ex-DPPs involved assessing their absorption spectra, molecular rigidity, and intermolecular packing geometries.
• Evaluation of SF efficiency was performed based on the molecular design and observed photophysical properties.

Main Results:

• The novel Ex-DPPs exhibit strong absorption with a fivefold higher extinction coefficient compared to conventional DPPs.
• These chromophores possess good molecular rigidity, effectively suppressing non-radiative deactivation pathways.
• The expanded π-skeleton facilitates well-suited intermolecular packing, promoting efficient singlet fission processes.

Conclusions:

• The developed Ex-DPPs represent a new class of high-efficiency singlet fission chromophores.
• These findings provide valuable insights and design principles for creating advanced SF materials for solar energy applications.
• The study addresses the need for improved SF materials to boost the practical efficiency of solar energy conversion devices.