Improved electron collection in fullerene via caesium iodide or carbonate by means of annealing in inverted organic solar cells
1 L’UNAM, Université de Nantes, MOLTECH-Anjou, CNRS, UMR 6200, 2 rue de la Houssinière, BP 92208, 44000 Nantes, France
2 Laboratoire Optoélectronique et Physico-chimie des Matériaux, Université Ibn Tofail, Faculté des Sciences, BP 133, 14000 Kenitra, Morocco
3 Université de Nantes, Institut des Matériaux Jean Rouxel (IMN), CNRS, UMR 6502, 2 rue de la Houssinière, BP 32229, 44322 Nantes Cedex 3, France
4 Laboratory for Unconventional Electronics and Photonics, Department of Physics, National Institute of Technology, 673 601 Calicut, Kerala, India
5 L’UNAM, Université de Nantes, Faculté des Sciences et des Techniques, 2 rue de la Houssinière, BP 92208, 44000 Nantes, France
Received: 27 November 2013
Accepted: 16 January 2014
Published online: 6 May 2014
Inverted organic photovoltaic cells (IOPVCs), based on the planar heterojunction C60/CuPc, were grown using MoO3 as anode buffer layer and CsI or Cs2CO3 as cathode buffer layer (CBL), the cathode being an ITO coated glass. Work functions, Φf, of treated cathode were estimated using the cyclic voltammetry method. It is shown that Φf of ITO covered with a Cs compounds is decreased. This decrease is amplified by the annealing. It is shown that the thermal deposition under vacuum of the CBL induces a partial decomposition of the caesium compounds. In parallel, the formation of a compound with the In of ITO is put in evidence. This reaction is amplified by annealing, which allows obtaining IOPVCs with improved efficiency. The optimum annealing conditions is 150 °C for 5 min.
© El Jouad et al., published by EDP Sciences, 2014
This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.