Improvement of pentathiophene/fullerene planar heterojunction organic photovoltaic cells through MoO3/CuI anode buffer bilayer
Résumé
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/ABL/Pentathiophene/fullerene /Alq3/Al with ABL = 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 ABL. In order to understand these results the pentathiophene films deposited onto the different ABLs 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.