Date of Award

2019-01-01

Degree Name

Master of Science

Department

Physics

Advisor(s)

Rajendra R. Zope

Abstract

The photovoltaic active materials composed of endohedral metafullerene and phthalocyanine derivatives are known as excellent electron donor-acceptor pairs. The tri-metallic nitride endohedral C80 fullerene exhibits high absorption coefficients in the visible region of the spectrum and has similar electron-accepting abilities as that of C60 fullerene, which can allow for higher efficiencies in OPV devices. In this study, we examine the effect of solvent on the charge transfer excitation energies of Sc3N@C80-ZnPc and Sc3N@C80-H2Pc donor-acceptor molecular complexes. Three different solvents with different polarity - water, toluene, and acetone are used. The solvent is modeled as a polarizable continuum as implemented in our UTEP-NRLMOL code. The charge transfer excitation energy is proportional to the open circuit voltage which is a parameter that determines the efficiency of the photovoltaic cell. We compute the charge transfer excitation energies using the perturbative delta-SCF method developed in our laboratory. The charge transfer excitation energies, in general, decreases in solutions with respect to its gas phase values. The stabilization of charge-transfer states increases with increase in the solvent polarity. A detailed orbital analysis of the ground and excited states is performed. We find that the presence of solvents can reorder the orbitals of the solute complexes as compared to gas-phase orbital order as well change the character of the excited states. The effect of the solvent on local excitations are small as compared to the charge transfer excitations. We find that there are few pure charge transfer states for Sc3N@C80-ZnPc unlike in Sc3N@C80-H2Pc for each solvents taken

Language

en

Provenance

Received from ProQuest

File Size

71 pages

File Format

application/pdf

Rights Holder

Timilsina Prasad Timlsina

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