Applications of single-walled carbon nanotubes and type-II quantum dots in photovoltaics and passive mode-locking saturable absorbers

摘要

Using single-molecule confocal imaging techniques combined with time-correlatedsingle-photon counting we investigated the electron transfer (ET) rates to the single-walledcarbon nanotubes from various types of semiconductor hetero-nanocrystals oftype-I or type-II band alignment. We observed significantly larger ET rate for type-IIZnSe/CdS dot-in-rod nanostructures as compared to type-I spherical CdSe/ZnScore/shell quantum-dots, and to CdSe/CdS dot-in-rod structures. We demonstratedthat such rapid ET dynamics can compete with both Auger and radiativerecombination processes, leading to potentially more effective photovoltaicoperation. In another work, we used aligned single-walled carbon nanotubes assaturable absorbers for ps laser pulse generation. Using the vertical evaporationtechnique we fabricated saturable absorbers by transferring the water-soluble singlewall carbon nanotubes onto a hydrophilic quartz substrate. The fast recovery times ofthe absorber were measured to be 136 fs and 790 fs. The modulation depth of theabsorber was about 1.5%. Passive mode-locked Nd: GdVO4 laser using such anabsorber was demonstrated. The continuous wave mode-locked pulses with the pulseduration of 12.4 ps and the repetition of 120 MHz were achieved. The maximumaverage output power of the mode-locked laser is 2.4 W at the pump power of 13 W.Such a kind of absorbers has potential to be put into practical use.© (2012) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.