Electroluminescence Enhancement in Polymer Light-Emitting Diodes through Inelastic Scattering of Oppositely Charged Bipolarons

Abstract

Combining the one-dimensional tight-binding Su-Schrieffer-Heeger (SSH) model and the extended Hubbard model (EHM), the scattering and combination of oppositely charged bipolarons in conjugated polymers are investigated using a nonadiabatic evolution method. On the basis of this physical picture, bipolarons can scatter into a singlet biexcitonic state, in which two electrons and two holes are trapped together by a lattice distortion. This biexcitonic state can emit one photon to an exciton state, which can subsequently decay to the ground state. The results indicate that the scattering and combination of oppositely charged bipolarons may provide guidance for improving the internal quantum efficiency for electroluminescence to as high as 75% in polymer light-emitting diodes.

Charge Carrier Scattering in Polymers: A New Neutral Coupled Soliton Channel

“…Alongside the new excited species yielded in the present study, other kind of beasts, such as excitons and biexcitons, were also obtained. As these later ones were already observed in other theoretical studies reported in literature 7,8,31–35 , their behavior, although of importance, will not be focus of our attention here in favor of discussing the previously unreported channel. In the numerical realizations performed in the present work, the new found product is noted to take place for U , α , and E 0 ranging between 1.0–4.0 eV, 4.6–5.6 eV/Å, and 1.0–1.5 mV/Å, respectively.…”

“…This kind of quasi-particle, in turn, is spinless and present charge ±3 e . It is already well accepted that an electron-bipolaron (negatively charged particle) and a hole-bipolaron (positively charged particle) may recombine to form a mixed state composed of bipolarons and excitons 7–10 . The light emission phenomenon results from the radiative decay of this kind of excited particle.…”

Same polarity polaron and bipolaron scattering on conducting polymers

“…Several studies has been carried out on the dynamics of scattering involving opposite charged quasi-particles [7][8][9][10][11], but we could not find any on quasi-particles with same sign charges. The present work addresses such situations in pristine chains of cispolyacetilene and polyparaphenylene, both simple and prototypical polymers whose analysis is relatively easy and can shed light on more complex systems.…”

Shaping PEDOT nanoparticles for use in 3D tissue phantoms

“…has previously shown, synthesis of PEDOT nanoparticles using soft templating leads to oxidation of the particles corresponding to strong NIR absorption due to polaron and bipolaron formation . Polaron decay is ideal for enhancing the photothermal potential of PEDOT for medical use . Both PEDOT NS and NF have broad optical absorption throughout the infrared region, as shown in Figure .…”

“…8 Polaron decay is ideal for enhancing the photothermal potential of PEDOT for medical use. [44][45][46] Both PEDOT NS and NF have broad optical absorption throughout the infrared region, as shown in Figure 2. The Raman spectrum of our synthesized NF, as shown in Figure 3, matches closely with the signature of commercially purchased PEDOT nanotubes, even though the commercial material has a more rounded "pillow-type" instead of tubular morphology.…”