Luminescent Solar Concentrators Employing Semiconducting Polymers

Applications

Applications for this technology are found in solar concentrators.

Problem Addressed

Luminescent solar concentrators (LSCs) are strategic, cost-effective, and scalable solutions for the convenient incorporation of photovoltaic (PV) technology into building infrastructures or other electronic architectures. LSCs consist of transparent slabs of plastic or glass that guide the emission of sunlight-absorbing photoluminescent dyes to their edges, where small and efficient PV devices may be attached. Perylene bisimides (PBIs) are valued as LSC emitters because of their exceptionally high photoluminescence quantum efficiencies and photostability. However, due to their small Stokes shifts, these materials often suffer from non-radiative reabsorption processes that severely curb their optical efficiencies in LSCs of commercially relevant sizes.

Technology

This invention relates to an LSC that employs two luminescent conjugated polymers as surrogate absorbers to amplify the emission of small amounts of a PBI  through an energy transfer cascade. Poly(aryleneethynylene)s (PAE) of varying optical bandgaps as surrogate absorbers for minute amounts of a commercially available and popular LSC dye . The optical bandgaps of the polymers are designed such that their corresponding absorption spectra cover a significant fraction of the solar spectrum, but are entirely decoupled from the emission of the PBI. Upon excitation by sunlight, a thin film comprised of the polymers and minority PBI emits photons that are guided into a transparent glass slab and consequently directed to its edges through total internal reflection. A key structural feature of the polymers is a pentiptycene repeat unit that prevents solid-state photoluminescence quenching and hampering of energy transfer processes.

Advantages

  • High solubility in organic solvents for simple processing into thin films 
  • Relatively low refractive indices for waveguide compatibility with inexpensive glass substrates