The quantum maximum of solar cells reached 7% which is half way to its DSSC counterparts. Actively explored issues concerning these semiconductor sensitized solar cells basically involve the four building blocks of the devices: wide band-gap material, counter electrode, electrolyte and the sensitizer. Improvements in such class of solar cells thus result from optimization studies in general. Since after the seminal paper by O´Regan and Graetzel which brought the idea of a low cost and highly efficient photoelectrochemical cells sensitized by dyes, the scientific community was flooded with enormous findings investigating the working mechanisms, designing new architectures, and synthesizing novel functional materials for energy conversion. However, the solar revolution is still floating around waiting for further advances in science and technology surpassing current success points.
The following shows a preliminary result and an overview of the current investigations on quantum dot and dye hybrid solar cells utilizing liquid electrolytes and their implications in the field of energy conversion. Dye sensitized solar cells have already developed into modules as low cost alternatives in harvesting light from the sun. It is far from the reach to the theoretical limit waiting for a novel approach and/or materials coming into the breakthrough. A possible means is employing nanocrystals absorbing light in the remaining region of the solar spectra other than the dyes harvest light. Quantum dots can thus be good candidates harnessing in the visible and near infrared regions. Typically, CdS, CdSe, AgS, PbS and PbSe quantum dots synthesized by robust methods colloidally or through the successive ionic layer adsorption and reaction are shown coupled with dyes to improve cell performance.