Star-shaped organic semiconductors with planar triazine core and diketopyrrolopyrrole branches for solution-processed small-molecule organic solar cells

摘要

A series of novel triazine-cored, star-shaped, conjugated molecules have been synthesized as donor materials for small molecule based organic solar cells. The structural features of these star-shaped molecules include a planarized triazine as the central core, 2,5-thienyl diketopyrrolopyrrole and 1,4-phenylene diketopyrrolopyrrole as the pi-conjugated bridge, and tert-butyl-substituted triphenylamine and tert-butyl-substituted carbazole as the role of end groups and donor units. Photovoltaic properties of the solar cells based on the star-shaped molecule with 2,5-thienyl diketopyrrolopyrrole branches were much better than those of the solar cells based on the one with 1,4-phenylene diketopyrrolopyrrole branches. A power conversion efficiency of 1.57%, a short-circuit current density of 6.34 mA/cm(2), an open-circuit voltage of 0.73 V, and a fill factor of 0.34 were observed for the organic solar cell based on the star-shaped molecule with 2,5-thienyl diketopyrrolopyrrole branches. (C) 2014 Elsevier Ltd. All rights reserved.