Optical gain and high quantum efficiency of matrix-free, closely packed CdSe quantum dots

Solid films of matrix-free, closely packed CdSe nanocrystals have been prepared and surface stabilized. An efficient suppression of nonradiative recombination channels is achieved. The absolute quantum efficiency has been determined spectrally resolved using an integrating sphere, and values between 1% and 10% are obtained in dependence on temperature. Spectrally broad optical gain has been found with the maximum around 510 nm.