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 Figure 1: Relative abundance of different metals in the Earth's continental crust in units of atoms of the element per 10 6 atoms of silicon. Figure adapted from Ref. [1].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.