Three-Dimensional Morphology Control Yielding Enhanced Hole Mobility In Air-Processed Organic Photovoltaics: Demonstration With Grazing-Incidence Wide-Angle X-Ray Scattering

Document Type

Article

Publication Date

6-16-2017

Department

Polymers and High Performance Materials

School

Mathematics and Natural Sciences

Abstract

Polymer organic photovoltaic (OPV) device performance is defined by the three-dimensional morphology of the phase-separated domains in the active layer. Here, we determine the evolution of morphology through different stages of tailored solvent vapor and thermal annealing techniques in air-processed poly(3-hexylthiophene-2,5-diyl)/phenyl-C61-butyric acid methyl ester-based OPV blends. A comparative evaluation of the effect of solvent type used for vapor annealing was performed using grazing-incidence wide-angle X-ray scattering, atomic force microscopy, and UV–vis spectroscopy to probe the active-layer morphology. A nonhalogenated orthogonal solvent was found to impart controlled morphological features within the exciton diffusion length scales, enhanced absorbance, greater crystallinity, increased paracrystalline disorder, and improved charge-carrier mobility. Low-boiling, fast-diffusing isopropanol allowed the greatest control over the nanoscale structure of the solvents evaluated and yielded a cocontinuous morphology with narrowed domains and enhanced paths for the charge carrier to reach the anode.

Publication Title

ACS Applied Materials & Interfaces

Volume

9

Issue

9

First Page

22764

Last Page

22772

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