Synthesis Of Ⅰ-Ⅲ-Ⅵ Semiconductor Quantum Dots And Their Use In Ⅰ-Ⅲ-Ⅵ Quantum Dot Sensitized Solar Cells

I-III-VI semiconductor nanocrystals is a kind of materials which consisted by the group of I(Cu, Ag), III(Ga, In), VI(S, Se), and other elements. They are direct narrow bandgap semiconductors. Specifically, Cu In S2 and Cu In Se2 match well with the solar spectra with band gaps of 1.5 e V and 1.04 e V, respectively. Cu In S2 and Cu In Se2 are good candidates as light absorption layer material in solar cell. When the sizes of nanocrystals are almost equal with the exciton radius, quantum confined effect will be dominated, exhibiting potentials in the fields of quantum dot-sensitized solar cells(QDSSC). Currently, the main synthesis methods of quantum dots sensitizer can be classified into two types: the pre-synthsis method and the in-situ synthesis method.In the thesis, the Cu2S/FTO counter electrode and I-III-VI quantum dots sensitizer were prepared. And their applications in QDSSC were investigated. The main contents are as follows:The precursor decomposition method was used to synthesize Cu2 S nanocrystals. Cu2 S nanocrystals were dispersed in organic solvent to form nanocrystals inks and then the ink was dropped onto FTO conductive glass. The formed Cu2 S nanocrystal thin film was annealed to remove the surface ligands and increase adhesive strength of thin film to obtain stable Cu2S/FTO counter electrode. Typical QDSSC were assembled with the Cd S-sensitized Ti O2 anode, Cu2S/FTO counter electrode, and S2-/Sn2-electrolyte. Their performances were tested by J-V and IPCE. The results show that the efficiency is much higher than the platinum electrode and the highest power conversion efficiency(PCE) is close to 3%.The Cu In S2/Cd S core-shell quantum dots and Cu In SexS2-x alloy quantum dots were synthesized using the solution-based method, and characterized by TEM, UV, PL, XRD and ICP-OES. The quantum dots were connected to Ti O2 anode by electrophoretic deposition(EPD) method or bifunctional molecules assited method. The QDSSCs were assembled and their performances were investigated. Results show that Cd S shell on the surface of Cu In S2 quantum dots core can improve the fluorescence performance and the cell performance. PCE was 1.17% for Cu In S2 based QDSSCs. Cu In SexS2-x alloy quantum based QDSSCs can extend light response range from 700 nm to 750 nm. The PCE and external quantum efficiency of QDSSCs were also improved.