TY - JOUR
TI - Suppressing the Photocatalytic Activity of Zinc Oxide Electron-Transport Layer in Nonfullerene Organic Solar Cells with a Pyrene-Bodipy Interlayer
AU - Soultati, A.
AU - Verykios, A.
AU - Panagiotakis, S.
AU - Armadorou, K.-K.
AU - Haider, M.I.
AU - Kaltzoglou, A.
AU - Drivas, C.
AU - Fakharuddin, A.
AU - Bao, X.
AU - Yang, C.
AU - Yusoff, A.R.B.M.
AU - Evangelou, E.K.
AU - Petsalakis, I.
AU - Kennou, S.
AU - Falaras, P.
AU - Yannakopoulou, K.
AU - Pistolis, G.
AU - Argitis, P.
AU - Vasilopoulou, M.
JO - ACS Applied Materials and Interfaces
PY - 2020
VL - 12
TODO - 19
SP - 21961-21973
PB - American Chemical Society
SN - null
TODO - 10.1021/acsami.0c03147
TODO - Charge transfer;  Conversion efficiency;  Electron transport properties;  Organic solar cells;  Oxide films;  Photocatalytic activity;  Pyrene;  Zinc oxide, Degradation reaction;  Degree of crystallization;  Electron transport layers;  Intra-molecular charge transfer;  Photoactive layers;  Power conversion efficiencies;  Surface work functions;  Thin interlayers, II-VI semiconductors
TODO - Organic solar cells based on nonfullerene acceptors have recently witnessed a significant rise in their power conversion efficiency values. However, they still suffer from severe instability issues, especially in an inverted device architecture based on the zinc oxide bottom electron transport layers. In this work, we insert a pyrene-bodipy donor-acceptor dye as a thin interlayer at the photoactive layer/zinc oxide interface to suppress the degradation reaction of the nonfullerene acceptor caused by the photocatalytic activity of zinc oxide. In particular, the pyrene-bodipy-based interlayer inhibits the direct contact between the nonfullerene acceptor and zinc oxide hence preventing the decomposition of the former by zinc oxide under illumination with UV light. As a result, the device photostability was significantly improved. The π-πinteraction between the nonfullerene acceptor and the bodipy part of the interlayer facilitates charge transfer from the nonfullerene acceptor toward pyrene, which is followed by intramolecular charge transfer to bodipy part and then to zinc oxide. The bodipy-pyrene modified zinc oxide also increased the degree of crystallization of the photoactive blend and the face-on stacking of the polymer donor molecules within the blend hence contributing to both enhanced charge transport and increased absorption of the incident light. Furthermore, it decreased the surface work function as well as surface energy of the zinc oxide film all impacting in improved power conversion efficiency values of the fabricated cells with champion devices reaching values up to 9.86 and 11.80% for the fullerene and nonfullerene-based devices, respectively. © 2020 American Chemical Society.
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