Engineering Two-Phase and Three-Phase Microstructures from Water-Based Dispersions of Nanoparticles for Eco-Friendly Polymer Solar Cell Applications

Natalie Holmes, Melissa Marks, James Cave, Krishna Feron, Matt Barr, Adam Fahy, Anirudh Sharma, Xun Pan, David Kilcoyne, Xiaojing Zhou, David Lewis, Mats R. Andersson, Jan van Stam, Alison B. Walker, Ellen Moons, Warwick Belcher, Paul Dastoor

    Research output: Contribution to journalArticlepeer-review

    22 Citations (Scopus)

    Abstract

    Nanoparticle organic photovoltaics, a subfield of organic photovoltaics (OPV), has attracted increasing interest in recent years due to the eco-friendly fabrication of solar modules afforded by colloidal ink technology. Importantly, using this approach it is now possible to engineer the microstructure of the light absorbing/charge generating layer of organic photovoltaics; decoupling film morphology from film deposition. In this study, single-component nanoparticles of poly(3-hexylthiophene) (P3HT) and phenyl-C 61 butyric acid methyl ester (PC 61 BM) were synthesized and used to generate a two-phase microstructure with control over domain size prior to film deposition. Scanning transmission X-ray microscopy (STXM) and electron microscopy were used to characterize the thin film morphology. Uniquely, the measured microstructure was a direct input for a nanoscopic kinetic Monte Carlo (KMC) model allowing us to assess exciton transport properties that are experimentally inaccessible in these single-component particles. Photoluminescence, UV-vis spectroscopy measurements, and KMC results of the nanoparticle thin films enabled the calculation of an experimental exciton dissociation efficiency (η ED ) of 37% for the two-phase microstructure. The glass transition temperature (T g ) of the materials was characterized with dynamic mechanical thermal analysis (DMTA) and thermal annealing led to an increase in η ED to 64% due to an increase in donor-acceptor interfaces in the thin film from both sintering of neighboring opposite-type particles in addition to the generation of a third mixed phase from diffusion of PC 61 BM into amorphous P3HT domains. As such, this study demonstrates the higher level of control over donor-acceptor film morphology enabled by customizing nanoparticulate colloidal inks, where the optimal three-phase film morphology for an OPV photoactive layer can be designed and engineered.

    Original languageEnglish
    Pages (from-to)6521-6531
    Number of pages11
    JournalChemistry of Materials
    Volume30
    Issue number18
    DOIs
    Publication statusPublished - 25 Sep 2018

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