A thermal conductivity and phase transition heat transfer mechanism has an opto-luminescent phosphor contained within the vapor chamber of the mechanism. The housing includes a section that is thermally conductive and a member that is at least partially optically transmissive, to allow emission of light produced by excitation of the phosphor. A working fluid also is contained within the chamber. The pressure within the chamber configures the working fluid to absorb heat during operation of the lighting device, to vaporize at a relatively hot location at or near at least a portion of the opto-luminescent phosphor as the working fluid absorbs heat, to transfer heat to and condense at a relatively cold location, and to return as a liquid to the relatively hot location. Also, the working fluid is in direct contact with or contains at least a portion of the opto-luminescent phosphor.