Siloxane Decorated Water-Obstructing Guest for Efficient Air-Processed OSCs

Area of Science:

• Materials Science
• Renewable Energy Engineering
• Organic Electronics

Background:

• Organic solar cells (OSCs) face significant challenges in ambient stability and processability, especially for large-area air-processed applications.
• Water-induced degradation of the active layer is a critical bottleneck limiting the development and commercialization of OSCs.
• Existing strategies often struggle to balance moisture protection with maintaining optimal film morphology.

Purpose of the Study:

• To develop a water-obstructing guest (WOG) strategy to improve the ambient stability and processability of organic solar cells (OSCs).
• To investigate the role of a siloxane-containing polymer (D18-SiO) as a WOG in mitigating water-induced degradation.
• To evaluate the impact of the WOG strategy on device performance, film morphology, and long-term stability under high relative humidity (RH).

Main Methods:

• Introduction of a siloxane-containing polymer (D18-SiO) as a water-obstructing guest (WOG) into the active layer blend.
• Fabrication of OSCs using both spin-coating and blade-coating techniques across a range of relative humidity (RH) conditions.
• Characterization of film morphology, trap density, and device performance (PCE) under varying RH levels.
• Long-term stability testing of unencapsulated OSCs under continuous illumination and ambient conditions (≈40% RH).

Main Results:

• OSCs fabricated with the D18-SiO WOG strategy achieved power conversion efficiencies (PCE) exceeding 19% (spin coating) and 17% (blade coating at 90% RH).
• The WOG strategy effectively suppressed trap density and preserved ideal nano-micromorphology, characterized by high crystallinity and tight packing.
• Unencapsulated OSCs retained 80.7% of their initial performance after 600 hours of continuous operation under light illumination in air (≈40% RH).

Conclusions:

• The proposed WOG strategy using D18-SiO is highly effective in enhancing the ambient stability and processability of air-processed OSCs.
• This approach provides a protective barrier against moisture, crucial for the development of durable and scalable organic solar technologies.
• The demonstrated potential for large-scale production highlights the WOG strategy as a promising pathway for advancing the commercial viability of OSCs.