Optimisation of the interface “organic material/aluminium” of CuPc/C₆₀ based photovoltaic cells

¹ Université de Nantes, Nantes Atlantique Universités, LAMP, EA 3825, Faculté des Sciences et des Techniques, 2 rue de la Houssinière, BP 92208, 44000 Nantes, France
² Université de Badji-Mokhtar Annaba, Faculté des Sciences, Algeria

Corresponding author: jean-christian.bernede@univ-nantes.fr

Received: 2 April 2007
Accepted: 17 August 2007
Published online: 31 October 2007

Abstract

We report the influence of an exciton-blocking layer and/or an Al₂O₃ thin layer at the interface “organic acceptor/aluminium” on the efficiency of CuPc/C₆₀ based photovoltaic cells. The presence, or not, of a thin Al₂O₃ layer depends on the encapsulating process of the devices. In the case of glass/ITO/CuPc/C₆₀/Al cells, the presence of an Al₂O₃ thin layer at the interface “organic acceptor/aluminium” increases strongly the open circuit voltage of the cells but decreases slightly their short circuit current and fill factor. In the case of glass/ITO/CuPc/C₆₀/Alq₃/Al cells, the open circuit voltage is systematically higher than without Alq₃. However, in that case, the presence of Al₂O₃ does not improve significantly the cell performances. All these results are discussed in terms of series and shunt resistance values related to possible oxygen contamination and organic covalent action with the Al films. The effectiveness of these different phenomena depends on the presence, or not, of Alq₃ and/or Al₂O₃ layers.