Open AccessIn Operando GISAXS and GIWAXS Stability Study of Organic Solar Cells Based on PffBT4T‐2OD:PC 71 BM with and without Solvent Additive
Author(s) -
Yang Dan,
Löhrer Franziska C.,
Körstgens Volker,
Schreiber Armin,
Cao Bing,
Bernstorff Sigrid,
MüllerBuschbaum Peter
Publication year - 2020
Publication title -
advanced science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 5.388
H-Index - 100
ISSN - 2198-3844
DOI - 10.1002/advs.202001117
Subject(s) - crystallinity , grazing incidence small angle scattering , organic solar cell , materials science , chemical engineering , solvent , degradation (telecommunications) , solar cell , solvent effects , scattering , organic chemistry , chemistry , polymer , optics , composite material , optoelectronics , small angle neutron scattering , telecommunications , physics , neutron scattering , computer science , engineering
Solvent additives are known to modify the morphology of bulk heterojunction active layers to achieve high efficiency organic solar cells. However, the knowledge about the influence of solvent additives on the morphology degradation is limited. Hence, in operando grazing‐incidence small and wide angle X‐ray scattering (GISAXS and GIWAXS) measurements are applied on a series of PffBT4T‐2OD:PC 71 BM‐based solar cells prepared without and with solvent additives. The solar cells fabricated without a solvent additive, with 1,8‐diiodoctane (DIO), and with o ‐chlorobenzaldehyde (CBA) additive show differences in the device degradation and changes in the morphology and crystallinity of the active layers. The mesoscale morphology changes are correlated with the decay of the short‐circuit current J sc and the evolution of crystalline grain sizes is codependent with the decay of open‐circuit voltage V oc . Without additive, the loss in J sc dominates the degradation, whereas with solvent additive (DIO and CBA) the loss in V oc rules the degradation. CBA addition increases the overall device stability as compared to DIO or absence of additive.