High-efficiency organic solar cells processed from a halogen-free solvent system

• The use of non-halogenated solvents for the green manufacture of high-efficiency organic solar cells (OSCs) is important for their future application. However, the power conversion efficiency (PCE) of the non-halogenated solvent processed OSCs is generally lower than their halogenated counterpart due to the poor film microstructure caused by the solubility issue. Herein, we propose a halogen-free solvent system to optimize film microstructure of the photovoltaic blend based on the polymer donor D18 and small-molecule acceptor (SMA) L8-BO towards high-efficiency OSCs. The solvent system is consisted of a main solvent carbon disulfide and an additive paraxylene, where the former ensures the good solution-processability and promotes the solution aggregation of L8-BO, and the latter can finely control the phase-separation process by selectively dissolving the SMA. This solvent combination robustly produces a high-quality active layer, i.e., the bicontinuous networks of donor and acceptor with nano-sized phase-separation and strong & pi;-& pi; stacking. With the effective charge generation, transport and collection, the resulting device from the non-halogenated solvent system shows a high PCE of 17.50%, which is comparable to that of the device prepared from the halogenated solvent chloroform (ca. 17.11%). This article proposes a new strategy for the green fabrication of high-efficiency OSCs to accelerate their industrialization.

Ämnesord

NATURVETENSKAP  -- Kemi -- Annan kemi (hsv//swe)

NATURAL SCIENCES  -- Chemical Sciences -- Other Chemistry Topics (hsv//eng)

Nyckelord

organic solar cells; small molecule acceptor; film microstructure; non-halogenated solvent; solvent engineering

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