Conjugated systems are currently developed for their semi-conducting properties which can be used for the elaboration of electronic devices. This work focuses on the synthesis and the characterization of conjugated molecules as molecular donors for photovoltaic (PV) cells. After an introduction describing the principle of PV conversion and the different classes of active materials, it is shown that conjugated systems can represent an alternative to inorganic materials. A state of the art presents the main molecular structures leading to efficient PV cells. During this work, different approaches leading to molecular electron donor materials for PV cells have been developed. The first one is based on oligothiophenes showing a two-dimensional structure (Chapter 2). It is shown that desymmetrization of these systems or insertion of electron-accepting units leads to an improvement of the performances of the related solar cells. A second approach deals with the synthesis of new donor-acceptor (D-A) and donor-acceptor-donor (D-A-D) conjugated systems. The electron donor groups D consist of oligothienyl triarylamine derivatives. The originality of this work lies in the use of tetracyanobutadiene (Chapter 3) and indenothiophenyl malononitrile (Chapter 4) as electron-accepting units A. PV devices of simple architecture elaborated with these molecular donors have shown good performances.
