Integration of nanoscale light emitters: an efficient ultraviolet and blue random lasing from NaYF4:Yb/Tm hexagonal nanocrystals

Near infrared light-controlled release of payloads from ultraviolet-sensitive (UV-sensitive) polymer hydrogels or nanocarriers is one of the most promising strategies for biotherapy. Here, we propose the concept of light activation of NaYF4:20%Yb,2%Tm nanocrystals (NCs). NaYF4:20%Yb,2%Tm NCs are synthesized by a solvothermal method. Effective upconversion luminescence from NaYF4:20%Yb,2%Tm NCs excited by a continuous wave (CW) 980 nm laser is obtained. The NaYF4:20%Yb,2%Tm NCs are then used as a laser gain medium and sandwiched between Al and quartz reflectors to form laser microcavities. UV and blue upconverted random lasing is obtained from the laser microcavities. Hence, we verify explicitly that the NaYF4:Yb,Tm NCs support UV and blue upconversion random lasing via a 980 nm nanosecond laser excitation. Our work provides what we believe is a new concept for precision and localized cancer therapy by external light excitation.