TY - JOUR
T1 - In situ morphology studies of the mechanism for solution additive effects on the formation of bulk heterojunction films
AU - Richter, Lee J.
AU - DeLongchamp., Dean M.
AU - Bokel, Felicia A.
AU - Engmann, Sebastian
AU - Chou, Kang Wei
AU - Amassian, Aram
AU - Schaible, Eric G.
AU - Hexemer, Alexander
N1 - KAUST Repository Item: Exported on 2020-10-01
Acknowledgements: The authors wish to thank Jacquline Johnson and Edwin Chan for assistance in the development of the remote dispense system. Beamline 7.3.3 of the Advanced Light Source is supported by the Director of the Office of Science, Office of Basic Energy Sciences, of the U.S. Department of Energy under Contract No. DE-AC02-05CH11231.
PY - 2014/9/29
Y1 - 2014/9/29
N2 - The most successful active film morphology in organic photovoltaics is the bulk heterojunction (BHJ). The performance of a BHJ arises from a complex interplay of the spatial organization of the segregated donor and acceptor phases and the local order/quality of the respective phases. These critical morphological features develop dynamically during film formation, and it has become common practice to control them by the introduction of processing additives. Here, in situ grazing incidence X-ray diffraction (GIXD) and grazing incidence small angle X-ray scattering (GISAXS) studies of the development of order in BHJ films formed from the donor polymer poly(3-hexylthiophene) and acceptor phenyl-C61-butyric acid methyl ester under the influence of two common additives, 1,8-octanedithiol and 1-chloronaphthalene, are reported. By comparing optical aggregation to crystallization and using GISAXS to determine the number and nature of phases present during drying, two common mechanisms by which the additives increase P3HT crystallinity are identified. Additives accelerate the appearance of pre-crystalline nuclei by controlling solvent quality and allow for extended crystal growth by delaying the onset of PCBM-induced vitrification. The glass transition effects vary system-to-system and may be correlated to the number and composition of phases present during drying. Synchrotron X-ray scattering measurements of nanoscale structure evolution during the drying of polymer-fullerene photovoltaic films are described. Changes in the number and nature of phases, as well as the order within them, reveals the mechanisms by which formulation additives promote structural characteristics leading to higher power conversion efficiencies.
AB - The most successful active film morphology in organic photovoltaics is the bulk heterojunction (BHJ). The performance of a BHJ arises from a complex interplay of the spatial organization of the segregated donor and acceptor phases and the local order/quality of the respective phases. These critical morphological features develop dynamically during film formation, and it has become common practice to control them by the introduction of processing additives. Here, in situ grazing incidence X-ray diffraction (GIXD) and grazing incidence small angle X-ray scattering (GISAXS) studies of the development of order in BHJ films formed from the donor polymer poly(3-hexylthiophene) and acceptor phenyl-C61-butyric acid methyl ester under the influence of two common additives, 1,8-octanedithiol and 1-chloronaphthalene, are reported. By comparing optical aggregation to crystallization and using GISAXS to determine the number and nature of phases present during drying, two common mechanisms by which the additives increase P3HT crystallinity are identified. Additives accelerate the appearance of pre-crystalline nuclei by controlling solvent quality and allow for extended crystal growth by delaying the onset of PCBM-induced vitrification. The glass transition effects vary system-to-system and may be correlated to the number and composition of phases present during drying. Synchrotron X-ray scattering measurements of nanoscale structure evolution during the drying of polymer-fullerene photovoltaic films are described. Changes in the number and nature of phases, as well as the order within them, reveals the mechanisms by which formulation additives promote structural characteristics leading to higher power conversion efficiencies.
UR - http://hdl.handle.net/10754/563765
UR - http://doi.wiley.com/10.1002/aenm.201400975
UR - http://www.scopus.com/inward/record.url?scp=84922387835&partnerID=8YFLogxK
U2 - 10.1002/aenm.201400975
DO - 10.1002/aenm.201400975
M3 - Article
SN - 1614-6832
VL - 5
SP - 1400975
JO - Advanced Energy Materials
JF - Advanced Energy Materials
IS - 3
ER -