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Linking Vertical Bulk‐Heterojunction Composition and Transient Photocurrent Dynamics in Organic Solar Cells with Solution‐Processed MoO x Contact Layers
Author(s) -
Tremolet de Villers Bertrand J.,
MacKenzie Roderick C. I.,
Jasieniak Jacek J.,
Treat Neil D.,
Chabinyc Michael L.
Publication year - 2014
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.201301290
Subject(s) - materials science , photocurrent , heterojunction , polymer solar cell , organic solar cell , optoelectronics , solar cell , photoactive layer , hybrid solar cell , active layer , fullerene , analytical chemistry (journal) , nanotechnology , polymer , layer (electronics) , composite material , chemistry , thin film transistor , organic chemistry , chromatography
It is demonstrated that a combination of microsecond transient photocurrent measurements and film morphology characterization can be used to identify a charge‐carrier blocking layer within polymer:fullerene bulk‐heterojunction solar cells. Solution‐processed molybdenum oxide (s‐MoO x ) interlayers are used to control the morphology of the bulk‐heterojunction. By selecting either a low‐ or high‐temperature annealing (70 °C or 150 °C) for the s‐MoO x layer, a well‐performing device is fabricated with an ideally interconnected, high‐efficiency morphology, or a device is fabricated in which the fullerene phase segregates near the hole extracting contact preventing efficient charge extraction. By probing the photocurrent dynamics of these two contrasting model systems as a function of excitation voltage and light intensity, the optoelectronic responses of the solar cells are correlated with the vertical phase composition of the polymer:fullerene active layer, which is known from dynamic secondary‐ion mass spectroscopy (DSIMS). Numerical simulations are used to verify and understand the experimental results. The result is a method to detect poor morphologies in operating organic solar cells.