Synthesis and study of new small molecules for organic photovoltaic applications

This thesis describes the synthesis and characterisation of novel organic small molecules with potential optoelectronic application. In chapter one, a general introduction relating to photovoltaics and the different types of solar cells with an overview of the working principle of two types of these cells, bulk heterojunction solar cells (BHJSCs) and dye synthesis solar cells (DSSCs), including examples of some molecular designs of the best performing dyes is provide. Chapter two, describes the synthesis of a new library of phenothiazine based small molecules with A-π spacer-D- π spacer-A configuration. These molecules employed as a potential active donor material for BHJSCs, reporting a power conversion efficiency of 1% as the best result. In chapter three, two new molecules based on 2,1,3-Benzothiadiazole are synthesised and fully characterized for BHJSCs. These compounds used as donor component blended with PC71BM acceptor in the device, reporting a power conversion efficiency of 1.24 %. The main advantage of these compounds would be the easy two steps synthesis, starting from cheap starting materials. The fourth chapter includes the successful synthesis and characterization of three conjugated organic molecules based on phenothiazine and phenazine. These compounds employed as a HTMs for perovskite solar cells. Among these, two molecules containing methoxy triaryl amine on the nitrogen position (4.48 and 4.49) were tested, and the best reporting PCE reached 3.94 % and 5.47 respectively. Finally, the last chapter describes the synthesis and fully characterization of several phenothiazine and phenoxazine derivatives in order to explore their performance as a photosensitiser in DSSCs. All these dyes exhibit broad absorption spectra from 300 to 600 nm and will be tested by our collaborato