Structural characterization of phenyl-cored thiophene dendrimers for organic photovoltaics

Organic semiconductors have emerged as a possible approach allowing for large-scale, low-cost solar cell production of with sufficient power conversion efficiency to be commercially viable. Pi-conjugated dendrimers have been used in bulk heterojunction photovoltaic devices as a substitute for the conjugated polymer.[1] Dendrimers can be driven by strong pi-pi interactions yielding highly ordered film morphologies. Such molecular ordering is important for the efficient operation of polymer-fullerene blend devices. Here we characterize a series of previously synthesized dendrimers based on a phenyl-core with thiophene dendrons. XRD, AFM, and FTIR were used to provide information on the structural features of the newly synthesized dendrimers. Correlations between the number and length of the dendrimer arms and the degree of ordering of thin films are evident from the data. Such information elucidates the structure-property relationship of these materials and provides guidance in designing new generations of dendrimers for potential photovoltaic device development.