Dynamic dielectric screening and exciton binding energies in conjugated polymers

1997 ◽  
Author(s):  
Jason Weibel ◽  
David Yaron
Keyword(s):  
Conjugated Polymers ◽  
Binding Energies ◽  
Dielectric Screening

Excitons in Low-Dimensional Systems: Conjugated Polymers and Semiconductor Surfaces

1999 ◽  
Vol 579 ◽  
Author(s):  
Michael Rohlfing
Keyword(s):  
Conjugated Polymers ◽  
Transition Matrix ◽  
Optical Transition ◽  
Binding Energies ◽  
Semiconductor Surface ◽  
Matrix Elements ◽  
Excitation Energies ◽  
Transition Matrix Elements ◽  
Low Dimensional ◽  
Excitonic States

ABSTRACTWe investigate the formation of excitons in low-dimensional semiconducting systems. To this end a recently developed ab initio approach is employed to determine the excitation energies and optical transition matrix elements of bound and unbound excitonic states. From these results the optical spectrum can be evaluated. We discuss two classes of low- dimensional prototype materials: conjugated polymers and a semiconductor surface. Due to the reduced dimensionality, the excitonic binding energies are much larger than in con- ventional semiconductors.

scholarly journals Dielectric Screening Modulates Semicondcutor Nanoplatelet Excitons

2021 ◽  
Author(s):  
Ashley Shin ◽  
Azmain A. Hossain ◽  
Stephanie M. Tenney ◽  
Xuanheng Tan ◽  
Lauren A. Tan ◽  
...  
Keyword(s):  
Binding Energy ◽  
Relative Effect ◽  
Binding Energies ◽  
Exciton Binding Energy ◽  
Electrostatic Model ◽  
Excitonic Absorption ◽  
2D Semiconductors ◽  
Dielectric Screening ◽  
Device Properties ◽  
First Time

The influence of external dielectric environments is well understood for 2D semiconductor materials but is overlooked for colloidally-grown II-VI nanoplatelets (NPLs). In this work, we synthesize MX (M=Cd, Hg; X= Se, Te) NPLs of varying thicknesses, and apply a modified Elliott model to fit excitonic absorption features and report exciton binding energies for cadmium telluride and mercury chalcogenides for the first time. Our observations indicate that the exciton binding energy is modulated by the dielectric screening of semiconductor material by the external ligand environment. Furthermore, NPL binding energies show a dependence on the number of monolayers consistent with relative effect of internal vs. external dielectric. To describe this, we derive an analytical electrostatic model, reinforcing the hypothesis that the external environment increases the exciton binding energy relative to the bulk—due to the distortion of the Coulombic potential across the NPL surface. We further confirm this effect by decreasing and recovering the exciton binding energy of HgTe NPLs through washing in polarizable solvents. Our results illustrate that NPLs are colloidal analogues of Van der Waals 2D semiconductors and point to surface modification as an approach to control photophysics and device properties.

Coulomb screening and exciton binding energies in conjugated polymers

1997 ◽  
Vol 106 (10) ◽  
pp. 4216-4227 ◽  
Author(s):  
Eric Moore ◽  
Benjamin Gherman ◽  
David Yaron
Keyword(s):  
Conjugated Polymers ◽  
Binding Energies

scholarly journals Dynamical model of the dielectric screening of conjugated polymers

2004 ◽  
Vol 69 (15) ◽  
Author(s):  
William Barford ◽  
Robert J. Bursill ◽  
David Yaron
Keyword(s):  
Conjugated Polymers ◽  
Dynamical Model ◽  
Dielectric Screening

scholarly journals Dielectric Screening Modulates Semicondcutor Nanoplatelet Excitons

2021 ◽  
Author(s):  
Ashley Shin ◽  
Azmain A. Hossain ◽  
Stephanie M. Tenney ◽  
Xuanheng Tan ◽  
Lauren A. Tan ◽  
...  
Keyword(s):  
Binding Energy ◽  
Relative Effect ◽  
Binding Energies ◽  
Exciton Binding Energy ◽  
Electrostatic Model ◽  
Excitonic Absorption ◽  
2D Semiconductors ◽  
Dielectric Screening ◽  
Device Properties ◽  
First Time

The influence of external dielectric environments is well understood for 2D semiconductor materials but is overlooked for colloidally-grown II-VI nanoplatelets (NPLs). In this work, we synthesize MX (M=Cd, Hg; X= Se, Te) NPLs of varying thicknesses, and apply a modified Elliott model to fit excitonic absorption features and report exciton binding energies for cadmium telluride and mercury chalcogenides for the first time. Our observations indicate that the exciton binding energy is modulated by the dielectric screening of semiconductor material by the external ligand environment. Furthermore, NPL binding energies show a dependence on the number of monolayers consistent with relative effect of internal vs. external dielectric. To describe this, we derive an analytical electrostatic model, reinforcing the hypothesis that the external environment increases the exciton binding energy relative to the bulk—due to the distortion of the Coulombic potential across the NPL surface. We further confirm this effect by decreasing and recovering the exciton binding energy of HgTe NPLs through washing in polarizable solvents. Our results illustrate that NPLs are colloidal analogues of Van der Waals 2D semiconductors and point to surface modification as an approach to control photophysics and device properties.

Electronic structure studies of conducting polymers by electron energy-loss spectroscopy

1996 ◽  
Vol 54 ◽  
pp. 160-161
Author(s):  
J. Fink
Keyword(s):  
Electronic Structure ◽  
Conducting Polymers ◽  
Conjugated Polymers ◽  
Electron Acceptors ◽  
Electron Donors ◽  
Light Emitting ◽  
One Dimensional ◽  
New Class ◽  
Electrical Conductivities ◽  
Electron Energy Loss

Conducting polymers comprises a new class of materials achieving electrical conductivities which rival those of the best metals. The parent compounds (conjugated polymers) are quasi-one-dimensional semiconductors. These polymers can be doped by electron acceptors or electron donors. The prototype of these materials is polyacetylene (PA). There are various other conjugated polymers such as polyparaphenylene, polyphenylenevinylene, polypoyrrole or polythiophene. The doped systems, i.e. the conducting polymers, have intersting potential technological applications such as replacement of conventional metals in electronic shielding and antistatic equipment, rechargable batteries, and flexible light emitting diodes.Although these systems have been investigated almost 20 years, the electronic structure of the doped metallic systems is not clear and even the reason for the gap in undoped semiconducting systems is under discussion.

Sign in / Sign up

Export Citation Format

Share Document