Correlating the Polymorphism of Titanyl Phthalocyanine Thin Films with Solar Cell Performance.
The structure of titanyl phthalocyanine (TiOPc) thin films is correlated with photovoltaic properties of planar heterojunction solar cells by pairing different TiOPc polymorph donor layers with C60 as an acceptor. Solvent annealing and the insertion of two different templating layers, namely 1H,1H,2H,2H-perfluorodecyltrichlorosilane (FDTS) and CuI, prove to be effective methods to control the TiOPc thin film structure. The crystal phase of TiOPc thin films was identified by combining X-ray reflectivity (XRR) measurements with spectroscopic techniques, including absorption and micro-Raman measurements. Implementation of a donor layer with an absorption spectrum extending into the near-infrared (NIR) led to solar cells with external quantum efficiencies (EQEs) above 27% from λ = 600 - 890 nm, with the best device yielding a power conversion efficiency (PCE) of 2.6%. Our results highlight the need to understand the relationship between processing parameters and thin film structure, as these have important consequences on device performance.
†Imec, Kapeldreef 75, B-3001 Heverlee, Belgium.|‡Department of Metallurgy and Materials Engineering, KU Leuven, Kasteelpark Arenberg 44, B-3001 Heverlee, Belgium.
Karolien
K
Vasseur
†Imec, Kapeldreef 75, B-3001 Heverlee, Belgium.
Barry P
BP
Rand
†Imec, Kapeldreef 75, B-3001 Heverlee, Belgium.
David
D
Cheyns
§Instituut voor Kern- en Stralingsfysica, KU Leuven, Celestijnenlaan 200 D, B-3001 Heverlee, Belgium.
Kristiaan
K
Temst
‡Department of Metallurgy and Materials Engineering, KU Leuven, Kasteelpark Arenberg 44, B-3001 Heverlee, Belgium.
Ludo
L
Froyen
†Imec, Kapeldreef 75, B-3001 Heverlee, Belgium.|∥Department of Electrical Engineering, KU Leuven, Kasteelpark Arenberg 10, B-3001 Heverlee, Belgium.
Paul
P
Heremans
copper iodide; crystal phase; molecular orientation; planar heterojunction; self-assembled monolayer; solvent annealing; templating