Ordered Orientation and Compact Molecule Packing due to Coplanar Backbone Structure of Interlayer: Improvement in Fill Factor for Photovoltaic Device

Publication date: Available online 11 April 2019Source: European Polymer JournalAuthor(s): Doo Hun Kim, Woong Cheol Seok, Jong Tae Leem, Yong Woon Han, Ju Hui Kang, Ho Jun SongAbstractA novel alcohol/water-soluble small molecule was obtained using a p-type planar backbone. The synthesized molecule was dissolved in organic solvents and highly polar solvents. The 3,3'-(((3,3'''-dimethyl-[2,2':5',2'':5'',2'''-quarterthiophene]-5,5'''-diyl)bis(4,1-phenylene))bis(oxy))bis(N,N-dimethylpropan-1-amine) (QTA) film exhibited a red-shifted spectrum compared with the solution spectrum owing to its many more planar molecular conformations in the solid state. According to X-ray diffraction (XRD) measurements, the QTA film showed sharp diffraction peaks near 3.6–11.0°, which indicates the formation of an interdigitated and ordered structure as an out-of-plane peak (100) due to the alkyl side chain of the quarter-thiophene backbone. A comprehensive analysis of the out-of-plane and in-plane XRD data suggests that a large fraction of the QTA derivatives was oriented edge-on relative to the substrate. A photovoltaic device containing QTA exhibited an open-circuit voltage of 0.85 V, current density of 15.5 mA/cm2, fill factor of 62.9%, and power-conversion efficiency of 8.4%. The photovoltaic device containing the QTA derivative exhibited improved power conversion efficiency compared with those containing PFN (8.0%) due to the ordered orientation and compact molecule packing of QTA.Graphical ...
Source: European Polymer Journal - Category: Chemistry Source Type: research