  The energy sciences attempt to meet the increasing world-wide need for
energy, as well as sustainability goals, by cleaner sources of energy, by new
alternative sources of energy, and by more efficient uses of available energy.
These goals are entirely consistent with the principles of green chemistry.
This chapter concerns devices for creating electricity from light and for
creating light from electricity. The major focus is on the photoproperties of
ruthenium and iridium complexes, which have been proven to be a rich source of
inspiration for conceiving photoactivated devices, including organic
photovoltaic (OPV) cells and organic light emitting diodes (OLEDs). The chapter
reviews important already-in-use and potential applications of ruthenium and
iridium complex-based photodevices, including the underlying mechanism behind
their functioning and its investigation through computational chemistry
approaches. It highlights the role of the information obtained from
computational studies for the design of more efficient photodevices. The final
part complements the discourse with a review of the progress on greener
alternatives for OPVs and OLEDs.
