Morphological analysis of co-evaporated blend films based on initial growth for organic photovoltaics

Abstract

Bulk heterojunction structures composed of electron donor and acceptor molecules for application in high-performance organic photovoltaics studied. To fabricate these structures, the co-evaporation method in vacuum is commonly applied; however, the details of the crystal growth process during co-evaporation have not yet been established. Here, we focused on structural analysis of blend films composed of phthalocyanine and fullerene based on initial growth stage. Similar crystal growth behavior to that typically observed in single-component molecules is obtained for the films. These results suggest that the competitive crystal growth between donors and acceptors occurs during co-evaporation process. The balance of thin film growth among donor and acceptor molecules can be related to improved photovoltaic performance. The homogeneous blend structure leads to improvement of the power conversion efficiency from 1.2 % to 3.0 %.

Self‐Assembled Fullerene Nanostructures: Synthesis and Applications

“…In another instance, Shibata et al demonstrated a multilayered composite of ZnPc/C 60 which showed a rise in the power conversion efficiency of organic solar cell from 1.2% to 3.0%. [71] Using thermal coevaporation followed by thermal annealing technique, Singhal et al [72] also synthesized Au-C 60 nanocomposite and demonstrated that the gold deposition rate could be tuned to obtain 2 at% with 1.5 nm thickness. C/Pd films were developed by Rymarczyk et al [73] with pristine C 60 and palladium acetate as the precursors by the simultaneous thermal decomposition at low pressure.…”