Phase separation of co-evaporated ZnPc:C60 blend film for highly efficient organic photovoltaics

Abstract

We demonstrate phase separation of co-evaporated zinc phthalocyanine (ZnPc) and fullerene (C60) for efficient organic photovoltaic cells. With introducing a poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) film and a crystalline copper iodide film on indium tin oxide, 20-nm-thick ZnPc film adopts a lying-down crystalline geometry with grain sizes of about 50 nm. This surface distributed with strong interaction areas and weak interaction areas enables the selective growth of ZnPc and C60 molecules during following co-evaporation, which not only results in a phase separation but also improve the crystalline growth of C60. This blend film greatly enhances the efficiencies in photocurrent generation and carrier transport, resulting in a high power conversion efficiency of 4.56% under 1 sun.

Building interconnects in carbon nanotube networks with metal halides for transparent electrodes

“…Copper halides are p-type wide-bandgap semiconductors, thin films of which can be prepared by vacuum-or solution-based processes. Because of their compatible energy levels and strong interaction with organic molecules, our previous works have showed that copper halides can act as hole transport layers or structural templates for improving organic photovoltaics [35,36]. Here, we demonstrate the manipulation of halide crystallites in CNT networks at nanoscale by utilizing a pulse photonic curing system.…”

Interpenetrating heterojunction photovoltaic cells based on C60 nano-crystallized thin films

“…All of the C 60 films that were treated with solvent spin-coating or SVA exhibited an increase in absorption intensity between 300 to 500 nm compared to the untreated films. This absorption increase was caused by light scattering from the nanocrystals [32,33], and increase crystallinity of nanocrystallized C 60 films [34]. The UV-Vis absorption of the film subjected to SVA with n-C 6 H 14 changed significantly.…”

Predicting current from cross section images of organic photovoltaic devices

“…Unfortunately, defocused TEM has been shown to provide questionable results [12]. EFTEM creates a superior contrast and has been confirmed to work on P3HT:PCBM systems [3,17] as well as many other materials systems [19,20]. Combining EFTEM with the FIB cross section preparation technique, cross sections made from functioning devices give us the ability to see phase separation and charge collection pathways in actual devices.…”