Solvent-Induced Anti-Aggregation Evolution on Small Molecule Electron-Transporting Layer for Efficient, Scalable, and Robust Organic Solar Cells

The severe aggregation property of the small molecule electron-transporting layer (ETL) not only deteriorates the photovoltaic performance and operational reliability but also constrains its compatibility with large-scale coating techniques. Herein, by applying N,N '-Bis{3-[3-(Dimethylamino)propylamino]propyl}perylene-3,4,9,10-tetracarboxylic diimide (PDINN) (a well-known ETL) as a demo, a solvent-induced anti-aggregation (SIAA) strategy is proposed to cope with these hurdles via the mixing of ethanol and trifluoroethanol solvents at an optimal volume ratio. In situ photoluminescence and dynamic light scattering synergistically reveals the suppressed aggregation behavior of the SIAA-treated PDINN dispersion during the film-forming process. Owing to this amendment, the film quality and electron-transport capability of the PDINN layer are remarkably enhanced. In consequence, based on the PM6:L8-BO system, a champion power conversion efficiency (PCE) of 19.0% together with an impressive fill factor of 80.6% is harvested. A 1 cm(2 )device with an excellent PCE of 16.6% is also fabricated using the doctor-blading SIAA-treated PDINN ink. More strikingly, this SIAA treatment impels better reliability under long-term shelf-lifetime and thermal stress periods. This work provides a promising and tractable approach to address the inherent self-aggregation issue of electron-transporting materials, which is beneficial for the development of efficient and stable organic optoelectronic devices.

Automated summary

This study proposes a solvent-induced anti-aggregation strategy to improve the film quality and electron-transport capability of small molecule electron-transporting layers (ETL). This approach not only addresses the aggregation issue but also leads to efficient and stable organic optoelectronic devices.