Surface transformation and photoinduced recovery in CdSe nanocrystals

CdSe nanocrystals in solution and films can enter a metastable state in which the highly luminescent nanocrystals become dark. This change, which we attribute to a surface transformation, can be caused by heating or by changing the environment of the nanocrystals at room temperature. The metastable transformation is reversed upon illumination of above-band-gap light, at which point the nanocrystals are again highly luminescent.