Diffusion coefficient of charge carriers in disordered semiconductors retaining a combination of exponential and Gaussian mobility-gap states: Application to amorphous selenium

2021 ◽  
Vol 39 (6) ◽  
pp. 062211
Author(s):  
Dilshad Hossain ◽  
M. Z. Kabir
Keyword(s):  
Diffusion Coefficient ◽  
Charge Carriers ◽  
Amorphous Selenium ◽  
Gap States ◽  
Mobility Gap ◽  
Disordered Semiconductors

scholarly journals Molecular Doping in Multi-Molecule Polymer-Dopant Complexes Shows Reduced Coulomb Binding

2020 ◽  
Author(s):  
Chuanding Dong ◽  
Stefan Schumacher
Keyword(s):  
Charge Transfer ◽  
Organic Semiconductors ◽  
Positive Charge ◽  
Charge Carriers ◽  
Mechanistic Study ◽  
Charge Transfer Complexes ◽  
Mobile Charge ◽  
Molecular Doping ◽  
Gap States ◽  
P Type

<p>The mechanistic study of molecular doping of organic semiconductors (OSC) requires</p><p>an improved understanding of the role and formation of integer charge transfer complexes</p><p>(ICTC) on a microscopic level. In the present work we go one crucial step beyond</p><p>the simplest scenario of an isolated bi-molecular ICTC and study ICTCs formed of</p><p>up to two (poly[2,6-(4,4-bis(2-ethylhexyl)-4H-cyclopenta[2,1-b,3,4-b”]dithiophene)-alt-4,7-(2,1,3-</p><p>benzothiadiazole)](PCPDT-BT) oligomers and up to two CN6-CP molecules. We find that depending</p><p>on geometric arrangement, complexes containing two conjugated oligomers and two</p><p>dopant molecules can show p-type doping with double integer charge transfer, resulting in either</p><p>two singly doped oligomers or one doubly doped oligomer. Interestingly, compared to an individual</p><p>oligomer-dopant complex, the resulting in-gap states on the doped oligomers are significantly</p><p>lowered in energy. Indicating that, already in the relatively small systems studied here, Coulomb</p><p>binding of the doping-induced positive charge to the counter-ion is reduced which is an elemental</p><p>step towards generating mobile charge carriers through molecular doping.</p>

scholarly journals Molecular Doping in Multi-Molecule Polymer-Dopant Complexes Shows Reduced Coulomb Binding

2020 ◽  
Author(s):  
Chuanding Dong ◽  
Stefan Schumacher
Keyword(s):  
Charge Transfer ◽  
Organic Semiconductors ◽  
Positive Charge ◽  
Charge Carriers ◽  
Mechanistic Study ◽  
Charge Transfer Complexes ◽  
Mobile Charge ◽  
Molecular Doping ◽  
Gap States ◽  
P Type

<p>The mechanistic study of molecular doping of organic semiconductors (OSC) requires</p><p>an improved understanding of the role and formation of integer charge transfer complexes</p><p>(ICTC) on a microscopic level. In the present work we go one crucial step beyond</p><p>the simplest scenario of an isolated bi-molecular ICTC and study ICTCs formed of</p><p>up to two (poly[2,6-(4,4-bis(2-ethylhexyl)-4H-cyclopenta[2,1-b,3,4-b”]dithiophene)-alt-4,7-(2,1,3-</p><p>benzothiadiazole)](PCPDT-BT) oligomers and up to two CN6-CP molecules. We find that depending</p><p>on geometric arrangement, complexes containing two conjugated oligomers and two</p><p>dopant molecules can show p-type doping with double integer charge transfer, resulting in either</p><p>two singly doped oligomers or one doubly doped oligomer. Interestingly, compared to an individual</p><p>oligomer-dopant complex, the resulting in-gap states on the doped oligomers are significantly</p><p>lowered in energy. Indicating that, already in the relatively small systems studied here, Coulomb</p><p>binding of the doping-induced positive charge to the counter-ion is reduced which is an elemental</p><p>step towards generating mobile charge carriers through molecular doping.</p>

Unipolar Flow of Charge Carriers in a Dense Gas with and without Consideration of Diffusion

1970 ◽  
Vol 25 (10) ◽  
pp. 1447-1452
Author(s):  
W. Dällenbach
Keyword(s):  
Diffusion Coefficient ◽  
Electric Field ◽  
Cross Section ◽  
Current Density ◽  
Charge Carriers ◽  
Einstein Relation ◽  
Dense Gas ◽  
Modified Equations ◽  
Basic Equations ◽  
And Diffusion

Abstract The basic equations for the unipolar, stationary, one-dimensional flow of charge carriers in a dense gas, characterized by mobility and diffusion coefficient, can be integrated numerically. The discharge gap generally has a finite length; as far as in the end cross-section either density of particles and intensity of electric field tend towards infinity, or the density of particles becomes zero. Which of these two cases occurs depends on the current density of the discharge and on the intensity of the electric field in the initial cross-section. The notions mobility and diffusion coefficient will lose their applicability close to a pole like singularity as well as in a "dilution to zero", so that from a certain cross-section onwards the continuation of discharge is determined by modified equations.It is shown that in case the diffusion component of the current density is neglected, the integrals of the basic equations change fundamentally. Neglecting the diffusion is inadmissible. This is finally a consequence of the relationship between mobility and diffusion coefficient, as expressed by the Einstein-relation.

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