Amplified Spontaneous Green Emission and Lasing Emission From Carbon Nanoparticles

In this work, the optical properties of carbon nanoparticles (CNPs) can be modulated by the dopant-N atom and sp(2) C-contents. CNPs prepared with the low urea mass ratio of 0.2:1 (CNP1) exhibit blue emission (maximum PL quantum yield: 15%). Increasing sp(2) C- and dopant-N atom contents, as determined in CNPs prepared with high urea mass ratio of 2:1 (CNP2), lead to green emission (maximum PL quantum yield up to 36% in ethanol aqueous solution). Amplified spontaneous emission (ASE) can be observed only in CNP2 ethanol aqueous solution. Green lasing emission is achieved from CNP2 ethanol aqueous solution in a linear long Fabry-Perot cavity, indicating the potential of CNP2 as a gain medium for lasing. CNP2 shows superior photostability compared with C545T dye. The green emission from CNP2 is speculated to arise from electron-hole recombination (intrinsic state emission). The high PL quantum yield and small overlap between absorption and emissions of CNP2 ethanol aqueous solution are the key factors in realizing lasing emission.