Localized Potential Regulation on Polymer Donor Backbone Suppresses Energetic Disorder for Efficient, Stable and...

Area of Science:

• Materials Science
• Organic Electronics
• Photovoltaics

Background:

• Low-crystallinity polymer donors (PDs) in organic solar cells (OSCs) suffer from high energetic disorder and short exciton diffusion lengths.
• These limitations hinder exciton dissociation, charge transport, device efficiency, stability, and scalability.

Purpose of the Study:

• To develop a localized potential regulation strategy for intrinsically suppressing energetic disorder in PDs.
• To improve the performance and stability of organic solar cells through precise polymer backbone engineering.

Main Methods:

• Introduced a strongly electron-deficient unit into the disordered backbone of the polymer donor DP1 to create DP10.
• Engineered enhanced backbone rigidity, optimized local electronic polarization, and improved miscibility with the acceptor L8-BO.
• Investigated the impact of these modifications on exciton binding energy, exciton-phonon coupling, and exciton diffusion length.

Main Results:

• DP10 exhibited reduced exciton binding energy and suppressed exciton-phonon coupling, extending exciton diffusion length from 15.5 to 19.9 nm.
• DP10-based devices showed balanced, trap-tolerant charge transport and reduced non-radiative recombination.
• Achieved a 19.51% power conversion efficiency (PCE) in DP10:L8-BO binary devices and a 20.57% PCE in ternary devices.
• A 15.1 cm² solar module demonstrated 17.20% efficiency with high fill factors.

Conclusions:

• Localized potential regulation is a powerful molecular design principle for PDs in OSCs.
• This strategy enables simultaneous high efficiency, thermal stability, and processing robustness.
• The developed DP10 polymer donor represents a significant advancement for next-generation organic solar cells.