University of Otago, New Zealand


Te Tari Hua-Ruanuku

Chris Larsen

contact photo
Chris Larsen
Supervisor: Dr Nigel T. Lucas
Tel: (03) 479 9089
Location: Science II, 3c3

Chris graduated his PhD in May 2016 and is currently a Swiss Government Excellence Postdoctoral Scholarship holder at the University of Basel, Switzerland.

Project Summary

Electron donor-acceptor (D-A) materials are a class of optically-active compounds, widely utilised in dye-sensitised solar cells, organic photovoltaics, organic light-emitting diodes, nonlinear optical devices, biological probes and as therapeutic agents. Despite their use in such a wide range of applications, many fundamental properties of D-A materials are still poorly understood.

This research investigated several previously unexplored aspects of the interaction between donor and acceptor and their influence on the electronic and photophysical properties of the materials, utilising polypyridyl acceptors with increasing levels of spectroscopic complexity: benzo[c][1,2,5]thiadiazole (btd), dipyrido[3,2 a:2ʹ,3ʹ c]phenazine (dppz) and 5,6,11,12,17,18-hexaazatripnaphthalene (hatn). The aspects of the D-A interaction investigated in this thesis are energetics, connectivity and additivity. Re(I) tricarbonyl complexes of the dppz ligands provide competing MLCT processes, the influence of which can be spectroscopically determined and used to characterise the strength of the interaction between donor and acceptor.

Specifically, energetics was investigated through tuning of the triarylamine (TAA) donor through peripheral substitution with electron-donating methoxy and electron-withdrawing cyano groups, connectivity was investigated in three ways: (1) as a function of the D-A distance, using linear, conjugated bridging units with minimal electronic influence – namely, the para-phenylenes and para-ethynylphenylene; (2) as a function of  the D-A torsion angle, through incorporation of electronically inert steric factors on either the donor or acceptor that restrict the D-A conformation; (3) as a function of the electronic influence of the bridging unit, using the conducting thienyl and insulating triazolyl bridges. Additivity was investigated through incorporation of varying numbers of donors around a hatn acceptor.