Quantum dots are interesting materials for application in efficiency enhancement of solar cells, mainly because of their unique optical properties, including size-dependent emission wavelengths, narrow emission profiles, and photostability. We made attempts to utilize microwave-assisted hydrothermal synthesis to prepare water-soluble CdTe QDs with different thiol containing ligands as capping reagents. Our method was able to synthesize green to infrared-emitting CdTe QDs with high speed. This thesis focuses on the preparation, characterizations, and applications of water soluble CdTe quantum dots. Using UV-visible absorbance and photoluminescence measurements, powder X-ray diffraction, TEM image, the optical and structural properities of CdTe quantum dots were explored. Through surface amido or carboxyl functional groups, GSH/CdTe QDs can be conjugated with folic acid for cell imaging, demonstrating their potentially broad application as biolabels. On the other hand, the CdTe@SiO2 on Si surface of solar cells are demonstrated to have promising potential for efficient solar spectral conversion in crystalline Si-based solar cells.