Process-Aid Solid Engineering Triggers Delicately Modulation of Y-Series Non-Fullerene Acceptor for Efficient Organic Solar Cells

• Volatile solids with symmetric π-backbone are intensively implemented on manipulating the nanomorphology for improving the operability and stability of organic solar cells. However, due to the isotropic stacking, the announced solids with symmetric geometry cannot modify the microscopic phase separation and component distribution collaboratively, which will constrain the promotion of exciton splitting and charge collection efficiency. Inspired by the superiorities of asymmetric configuration, a novel process-aid solid (PAS) engineering is proposed. By coupling with BTP core unit in Y-series molecule, an asymmetric, volatile 1,3-dibromo-5-chlorobenzene solid can induce the anisotropic dipole direction, elevated dipole moment, and interlaminar interaction spontaneously. Due to the synergetic effects on the favorable phase separation and desired component distribution, the PAS-treated devices feature the evident improvement of exciton splitting, charge transport, and collection, accompanied by the suppressed trap-assisted recombination. Consequently, an impressive fill factor of 80.2% with maximum power conversion efficiency (PCE) of 18.5% in the PAS-treated device is achieved. More strikingly, the PAS-treated devices demonstrate a promising thickness-tolerance character, where a record PCE of 17.0% is yielded in PAS devices with a 300 nm thickness photoactive layer, which represents the highest PCE for thick-film organic solar cells. 

Subject headings

NATURVETENSKAP  -- Fysik (hsv//swe)

NATURAL SCIENCES  -- Physical Sciences (hsv//eng)

Keyword

asymmetric configuration

organic solar cells

thickness-tolerance

volatile solid

Y-series molecules

Cell engineering

Efficiency

Excitons

Geometry

Phase separation

Thick films

Asymmetric configurations

Component distributions

Exciton splitting

Power conversion efficiencies

Process aid

Solids engineering

Symmetrics

Thickness tolerance

Y-series molecule

Molecules

Publication and Content Type

ref (subject category)

art (subject category)