Substituent effects on the geometric and electronic properties of tetracyano-p-quinodimethane (TCNQ): A theoretical study.
Electron acceptors are classes of molecules that are important in organic devices as they help to improve the conductivity of organic semiconducting molecules by forming p-type complexes or anion radical complexes. These molecules can be doped into hole transporting materials to provide good ohmic contact with the anode and to improve the carrier density of the hole transport layer. This results in organic light emitting devices (OLEDs) with low driving voltages and high power efficiencies. In this study we investigate a series of TCNQ derivatives with substituents expected to facilitate the electron acceptor capabilities of the quinones using density functional theory (DFT) and time-dependent density functional theory (TDDFT). As expected, the cyano substitution stabilizes both HOMO and LUMO energy levels, and increases the adiabatic electron affinity of the dopants. The stabilization effect on the LUMO levels is greater and as a result the narrowing of the HOMO-LUMO gap is seen. This fact was further confirmed by TD-DFT studies, energy of the computed S1 ← S0 transition red shifted upon CN substitution. However, perturbation to the ground state geometry is negligible and all anionic structures exhibits aromatization independent of substitution. Our study suggests that the substituted derivatives reported herein show promise as conductivity dopants
- Research Organization:
- Pacific Northwest National Lab. (PNNL), Richland, WA (United States). Environmental Molecular Sciences Lab. (EMSL)
- Sponsoring Organization:
- USDOE
- DOE Contract Number:
- AC05-76RL01830
- OSTI ID:
- 1074303
- Report Number(s):
- PNNL-SA-86292; 30795; BT0301000
- Journal Information:
- Molecular Simulation, 39(5):350-356, Vol. 39, Issue 5; ISSN 0892--7022
- Country of Publication:
- United States
- Language:
- English
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