X-ray microscopic investigation of molecular orientation in a hole carrier thin film for organic solar cells

Quentin Arnoux (1, 2, 3) , Benjamin Watts (4) , Sufal Swaraj (5) , Francois Rochet (1, 5) , Ludovic Tortech (2, 3)

1 LCPMR - Laboratoire de Chimie Physique - Matière et Rayonnement
2 LICSEN - Laboratoire Innovation en Chimie des Surfaces et NanoSciences
3 IPCM - Institut Parisien de Chimie Moléculaire
4 Paul Scherrer Institute c/o Institute of Particle Physics
5 SSOLEIL - Synchrotron SOLEIL

As dipyranylidenes are excellent hole carriers, applications in organic solar cells or organic light emitting diode are envisaged. In the present study, we investigate the morphology of 2,2′,6,6′-tetraphenyl-4,4′-dipyranylidene (DIPO-Ph$_4$) deposited under vacuum on a silicon nitride (Si$_3$N$_4$) substrate, a paradigmatic system for the study of molecular crystal/inorganic substrate interfaces. Samples with various coating ratios and different thermal treatments were prepared. The films were characterized by atomic force microscopy and scanning transmission X-ray microscopy to gain insight into material growth. The results show a change in orientation at a molecular level depending upon the evaporation conditions. We are now able to tailor an organic layer with a specific molecular orientation and a specific electronic behavior.

Keywords: Organic solar cells; Scanning Transmission X-ray Microscopy; Molecular orientation

Domains: Material chemistry

Quentin Arnoux, Benjamin Watts, Sufal Swaraj, Francois Rochet, Ludovic Tortech. X-ray microscopic investigation of molecular orientation in a hole carrier thin film for organic solar cells. Nano Research, 2017, 5, pp.2771-2782. ⟨10.1007/s12274-017-1907-6⟩. ⟨cea-01659809⟩