Eur. Phys. J. Appl. Phys. (2016) 74: 24603
https://doi.org/10.1051/epjap/2015150335

Regular Article

Improvement of pentathiophene/fullerene planar heterojunction photovoltaic cells by improving the organic films morphology through the anode buffer bilayer^*

¹ Université de Nantes, MOLTECH-Anjou, CNRS, UMR 6200, 2 rue de la Houssinière, BP 92208, 44000 Nantes, France
² LOPCM, 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 92208, 44000 Nantes, France
⁴ Departamento de Ciencia de los Materiales, Facultad de Ciencias Físicas y Matemáticas, Universidad de Chile, 2777 Casilla, Santiago, Chile
⁵ Laboratory for Molecular Photonics and Electronics, Department of Physics, National Institute of Technology, 673 601 Calicut, Kerala, India

^a e-mail: linda.cattin-guenadez@univ-nantes.fr

Received: 3 July 2015
Revised: 24 July 2015
Accepted: 23 September 2015
Published online: 3 May 2016

Abstract

Organic photovoltaic cells (OPVCs) are based on a heterojunction electron donor (ED)/electron acceptor (EA). In the present work, the electron donor which is also the absorber of light is pentathiophene. The typical cells were ITO/HTL/pentathiophene/fullerene/Alq₃/Al with HTL (hole transport layer) = MoO₃, CuI, MoO₃/CuI. After optimisation of the pentathiophene thickness, 70 nm, the highest efficiency, 0.81%, is obtained with the bilayer MoO₃/CuI as HTL. In order to understand these results the pentathiophene films deposited onto the different HTLs were characterized by scanning electron microscopy, atomic force microscopy, X-rays diffraction, optical absorption and electrical characterization. It is shown that CuI improves the conductivity of the pentathiophene layer through the modification of the film structure, while MoO₃ decreases the leakage current. Using the bilayer MoO₃/CuI allows cumulating the advantages of each layer.