Electronic-Structure Theory of Organic Semiconductors: Charge-Transport Parameters and Metal/Organic Interfaces

Abstract

We focus this review on the theoretical description, at the density functional theory level, of two key processes that are common to electronic devices based on organic semiconductors (such as organic light-emitting diodes, field-effect transistors, and solar cells), namely charge transport and charge injection from electrodes. By using representative examples of current interest, our main goal is to introduce some of the reliable theoretical methodologies that can best depict these processes. We first discuss the evaluation of the microscopic parameters that determine charge-carrier transport in organic molecular crystals, i.e., electronic couplings and electron-vibration couplings. We then examine the electronic structure at interfaces between an organic layer and a metal or conducting oxide electrode, with an emphasis on the work-function modifications induced by the organic layer and on the interfacial energy-level alignments.

Insights into Enhanced Visible-Light Photocatalytic Hydrogen Evolution of g-C3N4and Highly Reduced Graphene Oxide Composite: The Role of Oxygen

“…45 Here, our calculations are performed by using the Cambridge Serial Total Energy Package (CASTEP) 46 based on the plane-wave pseudopotential DFT methods. The norm-conserving pseudopotentials 5 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 are employed to describe the electron-ion interactions.…”

A density functional theory investigation of the electronic structure and spin moments of magnetite

“…More recently, hybrid exchange-correlation (XC) functionals including a fraction of the Hartree–Fock (HF) exchange have been applied, and have been particularly successful in describing the ground-state properties of a wide class of transition metal oxides [22]. While the influence of various XC methods on the electronic structure of the organic layers in organic–inorganic heterostructures has been extensively studied, a detailed description of the impact methodological impact on the electronic structure of metal oxides is still lacking [23]. …”

Nanoscale morphology and electronic coupling at the interface between indium tin oxide and organic molecular materials

“…As shown in equation 1,the electronic couplings between molecules at the interface and the metal electrode surface enter directly in the Marcus-Jortner equation for the evaluation of injection rates. However, as demonstrated by several previous works, 11,12,31,33,44,67,[75][76][77] the electronic coupling changes dramatically with the specific molecule/surface configuration. Therefore, the distribution of electronic couplings with the complex morphology at the interface is a prerequisite for correlating nanoscale molecular aggregation to the distribution of injection rates.…”

“…[1][2][3][4][5][6][7] In particular, the injection of charges from an electrode into an organic thin film is one of the processes that crucially affects the global functioning of OLEDs and OTFTs. [8][9][10][11] A quantitative and realistic description of the phenomena related to charge injection at the metal-organic interface, however, is still a very challenging task, requiring the interplay of several models for the simulation of interface morphology, electronic coupling and ultimately injection dynamics. The interface morphology can be predicted by molecular dynamics simulations, typically parameterized using density-functional calculations on small subsystems.…”