We produced high-quality bare CdSe Quantum Dots(QDs) using wet chemical synthetic methods. Nearly monodisperse CdSe QD nanocrystals were characterized by UV-VIS absorption and photoluminescence spectroscopies, X-ray Powder Diffraction, SEM, and TEM. XRD patterns and TEM images show that CdSe QDs are wurtzite crystalline structures. Using the bandgap-engineerible semiconductor quantum dots, we made a solar cell as one as one of the applications. Here we report experimental results on the QD-Polymer composites heterojunction solar cells which consist of inorganic photovoltaic materials, CdSe QDs and regioregular poly(3-hexylthiophene)(P3HT) polymer. We further analyzed characteristics of the solar cells in terms of detailed SEM images of the morphology of the QD-polymer composites. When our devices were tested under AM 1.5 Global solar conditions, we reported that a power conversion efficiency of 0.0001%, an open circuit voltage of 0.164V, a short-circuit current density of 1.04 x 10^-3mA/cm², a maximum power density is 4.67 x 10^-5mW/cm², and a Fill factor of 0.27 were obtained.