Giant Small-Molecule Donors With Controlled Backbone Planarity Afford High-Performance and Photostable Organic Solar...

Area of Science:

• Materials Science
• Organic Electronics
• Photovoltaics

Background:

• Commercialization of organic solar cells (OSCs) requires high power conversion efficiency (PCE) and long-term stability.
• Small-molecule donors (SMDs) offer advantages but struggle with morphological stability due to diffusion.
• Giant small-molecule donors (GSMDs) present a potential solution by increasing molecular size.

Purpose of the Study:

• Design and synthesize novel GSMDs with enhanced optoelectronic properties.
• Investigate the impact of molecular configuration on thermal and electrical properties.
• Develop efficient and photostable OSCs using GSMDs.

Main Methods:

• Synthesized two GSMDs: GSMD-syn and GSMD-anti, differing in alkyl side chain orientation.
• Fabricated and characterized OSCs using these GSMDs with the Y6 acceptor.
• Evaluated PCE, morphological stability, and photostability of the devices.

Main Results:

• GSMD-anti demonstrated superior performance due to reduced steric hindrance, enhanced crystallinity, and improved charge transport.
• GSMD-anti:Y6 based OSCs achieved a PCE of 15.4%, surpassing conventional SMDs (13.4%) and GSMD-syn (11.9%).
• Ternary devices with GSMD-anti reached 16.5% PCE, and GSMD-anti:Y6 OSCs showed significantly enhanced photostability (1510 h vs. 60 h).

Conclusions:

• The anti-configuration of GSMDs effectively suppresses molecular diffusion, leading to improved morphological and photostability.
• GSMDs, particularly GSMD-anti, represent a promising class of materials for high-performance and stable OSCs.
• This work provides a pathway for designing advanced materials for next-generation organic photovoltaics.