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

• 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-C61 butyric acid methyl ester (PC61BM) 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 (ηED) of 37% for the two-phase microstructure. The glass transition temperature (Tg) of the materials was characterized with dynamic mechanical thermal analysis (DMTA) and thermal annealing led to an increase in ηED 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 PC61BM 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.

Ämnesord

NATURVETENSKAP  -- Fysik (hsv//swe)

NATURAL SCIENCES  -- Physical Sciences (hsv//eng)

NATURVETENSKAP  -- Kemi (hsv//swe)

NATURAL SCIENCES  -- Chemical Sciences (hsv//eng)

Nyckelord

Amorphous films

Amorphous materials

Butyric acid

Cell engineering

Colloids

Deposition

Environmental protection

Excitons

Glass transition

Morphology

Nanoparticles

Polymer solar cells

Scanning electron microscopy

Sintering

Solar cells

Solar power generation

Synthesis (chemical)

Thermoanalysis

Thin films

Ultraviolet visible spectroscopy

D. dynamic mechanical thermal analyses (DMTA)

Donor-acceptor interfaces

Kinetic Monte Carlo modeling

Scanning transmission x ray microscopy

Solar-cell applications

Three phase microstructure

Two-phase microstructures

Water based dispersion

Microstructure

Physics

Fysik

Kemi

Chemistry

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