Experimentally Validated Model for the Prediction of the HOMO and LUMO Energy Levels of Boronsubphthalocyanines

Abstract

We report the rapid screening of phenoxyboronsubphthalocyanine (PhO-BsubPc) derivatives for sensitivity of their HOMO and LUMO energy levels (E H and E L) to substitution with electron-donating and electron-withdrawing functional groups using semiempirical methods. Subsequently, we have synthesized a selection of seven PhO-BsubPc derivatives, further modeled the seven derivatives using DFT methods, and measured or determined their respective E H and E L. We have used a combination of ultraviolet photoelectron spectroscopy (UPS), cyclic voltammetry (CV), and ultraviolet–visible (UV–vis) spectroscopy to correlate the computational predictions with experimental data. From these experimental and computational results, we have shown that E H and E L of PhO-BsubPcs are more sensitive to peripheral substitutions than to substitution on the axial phenoxylate. The frontier molecular orbitals, calculated using DFT methods, were found to be exclusively located on the boronsubphthalocyanine ligand among the seven PhO-BsubPc derivatives. A mathematical model correlating computational results with experimental data was determined which can be subsequently used to rapidly predict how structural factors influence the E H and E L to direct synthetic and engineering efforts.

The influence of molecular geometry on photophysical properties and self-assembly of phthalimide end-capped thiophene-based organic molecules

“…,27 DFT calculations showed a similar trend to the experimental data. The differences between the two sets of data is mainly attributed to the lower accuracy of DFT in predicting the HOMO-LUMO energies 28.…”

Boron Subphthalocyanines as Organic Electronic Materials

“…We then determined the positions of the frontier orbitals (and consequently their band gaps) using a mixture of cyclic voltametry (CV), ultraviolet photoemission spectroscopy (UPS), and UV−visible spectroscopy. The results were that for PhO-BsubPcs, the relative position within the molecule of the frontier orbitals had a minimal response to variations at both the peripheral and axial positions ( Figure 7), 13 whereas the energy levels of the HOMO and LUMO were six times more sensitive to substitution on the peripheral positions of the BsubPc as compared to substitution at the axial position. At the extremes of the range were 3,4-diMe-PhO- BsubPc and F 17 BsubPc, spanning a HOMO range from 5.42 to 6.65 eV and a LUMO range from 3.28 to 4.54 eV.…”

From chloro to fluoro, expanding the role of aluminum phthalocyanine in organic photovoltaic devices

“…For example, chloro aluminum Pc (Cl-AlPc) has been paired with C 60 for the fabrication of a planar heterojunction (PHJ) and blended organic photovoltaic (OPV) devices. [11][12][13][14] Moving one level down on the periodic table, and given the successful use of Cl-AlPc in OPV devices [5][6][7][8] we decided to look at the effect of substituting the axial chloride of Cl-AlPc with a fluoride and incorporate fluoro aluminum Pc (F-AlPc) into simple PHJ OPV devices. 10 Our group has recently been studying the incorporation of fluorine groups into boron subphthalocyanine (a sub-class of Pcs) which resulted in a decreases in sublimation temperature, a change in the solid-state arrangement (crystal structure) and a change in electrochemical properties.…”