The Porous Close Packed CdS Quantum Dots Sensitized Solar Cells

Quantμm dots (QDs) show many unique features, such as quantμm confinement effect, mini-band e ffect a nd m ulti-exciton ef fect, thus have hi gh photo-electronic conversion c apability. Therefore, it is expected that Q DS can boost the energy conversion efficiency of solar cells beyond the traditional Shockley and Queisser limit of 32 % and have potential application in solar cell.We exploit a new structure of semiconductor sensitized solar cells, where CdS QDs or nanocrystals are assembled into a spongy structure and decorated with organic molecules to s erve a s photoanode. UV-vis a bsorption, Nyquist impedance s pectra, combining w ith photocurrent de nsity-voltage characterization demonstrate tha t th e assembled CdS na nocrystals w ith porous ar chitecture can effectively captu re t he incoming light and allow thorough infiltration of electrolyte, while the decoration of organic molecules helps to accelerate hole-transfer. As a r esult, the solar cells with spongy structure show higher absorption, short-circuit-current de nsity, ope n-circuit voltage, and final performance than traditional semiconductor sensitized solar cells.Moreover, three-dimensional ordered c lose-packed QDs structure, w ith controlled QDs size, pore size and photoanode thickness was fabricated based on PS templates. The opt imal t hickness and annealing t emperature of t he por ous CdS structure is 2 .6μm a nd 400oC, respectively. Furthermore, it is f ound t hat electrodepositon additional CdS can improve the contact between quantμm dots, and therefore enhance ca rrier t ransportation. F inally, in or der t o improve the charge separation of close packed QDs, CdSe was electrodeposited on t op of CdS porus structure, which attributes to the high photoelectric conversion efficiency of 2.47%.