Planarized Star‐Shaped Oligothiophenes as a New Class of Organic Semiconductors for Heterojunction Solar Cells

Abstract

Although compounds 1 and 2 (see Figure) have comparable conjugation lengths, the characterization of vacuum evaporated thin solid films shows that the star‐shaped geometry of compound 1 favors a preferential horizontal orientation of the molecules onto the surface of the substrate, which results in a increase of the efficiency of the corresponding heterojunction solar cells under white‐light illumination by a factor of 20.