Premium
Depositing Fullerenes in Swollen Polymer Layers via Sequential Processing of Organic Solar Cells
Author(s) -
van Franeker Jacobus J.,
Kouijzer Sandra,
Lou Xianwen,
Turbiez Mathieu,
Wienk Martijn M.,
Janssen René A. J.
Publication year - 2015
Publication title -
advanced energy materials
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 10.08
H-Index - 220
eISSN - 1614-6840
pISSN - 1614-6832
DOI - 10.1002/aenm.201500464
Subject(s) - fullerene , materials science , polymer , solubility , chemical engineering , solvent , swelling , spin coating , layer (electronics) , organic solar cell , coating , polymer solar cell , evaporation , polymer chemistry , organic chemistry , nanotechnology , composite material , chemistry , physics , engineering , thermodynamics
Polymer solar cells are conventionally processed by coating a multicomponent mixture containing polymer, fullerene, solvent, and cosolvent. The photovoltaic performance strongly depends on the nanoscale morphology of the blend, which is largely determined by the precise nature of the solvent composition and drying conditions. Here, an alternative processing route is investigated in which the two active layer components are deposited sequentially via spin coating or doctor blading. Spin coating the fullerene from o ‐dichlorobenzene on top of the polymer provides virtually identical morphologies and photovoltaic performance. Using blade coating, the influence of the second‐layer solvent for the fullerene derivative is investigated in further detail. Different aromatic solvents are compared regarding swelling of the polymer layer, fullerene solubility, and evaporation rate. It is found that while swelling of the polymer by the second‐layer solvent is a necessity for sequential processing, the solubility of the fullerene derivative in this solvent has the strongest influence on solar cell performance. Homogeneous layers in which a sufficient amount of fullerene can infiltrate the polymer film can only be achieved when solvents are used that have a very high solubility for the fullerene and swell the polymer layer.