The utilization of light to produce useful responses holds much potential for changing the world through smart materials and photovoltaic systems. We report the utilization of a variety of carbon nanotube composites as photovoltaic devices or as optothermal materials for the controlled placement of heat. Toward carbon nanotube - polymer photovoltaics we have successfully shown supramolecular compatibilization and functional bilayer devices. Optothermal processes are shown to manipulate a variety of system variables: surface energy, surface tension, and pressure. By manipulating these variables interesting responses are produced. Optothermal surface energy control produced wettability switches of 70º on composite surfaces. Optothermally modulated surface tensions of fluids converted light into work in the form of controlled linear motion, rotational motion, and volumetric expansion. Optothermally heated liquids confined within impermeable microcapsules resulted in the phototriggerable release of chemicals on demand. This release allowed small molecule reactions and polymerizations to be remotely initiated in a spatially selective manner. These results lay the framework for the expansion of the field of advanced optothermally responsive materials.