The present relates in general to upconversion luminescence ("UCL") materials and methods of making and using same and more particularly, but not meant to be limiting, to Mn²⁺ doped semiconductor nanoparticles for use as UCL materials. The present invention also relates in general to upconversion luminescence including two-photon absorption upconversion, and potential applications using UCL materials, including light emitting diodes, upconversion lasers, infrared detectors, chemical sensors, temperature sensors and biological labels, all of which incorporate a UCL material.