The Structural Study Of Pbs Counter The Structural Study Of PbS Counter Electrode And TiO₂ Photoanode In Quantum Dot Sensitized Solar Cells

Quantum dot sensitized solar cells (QDSSCs) is one of most studied projects in solar cells recently. As the indispensable parts in the cell, their properties of counter and working electrode play very important roles in determing the efficiency of QDSSCs. In this thesis, we studied the effect sulfide PbS counter electrode and oxide TiO2 photoanode on the property of quantum dot sensitized solar cells. These include:1、PbS counter electrodes were prepared through a hydrothermal route and a chemical corrosion method using sulfur powder or thiourea as the sulfur source.Tafel curves and electrochemical impedance measurements showed that PbS counterelectrode prepared by hydrothermal route has higher catalytic property as compared to that of prepared by chemical corrosion route, while the use of sulfur powder is better than that of using thiourea as sulfur source. The product PbS were assembled into QDSSCs using CdS/CdSe/TiO2 as the photoanod.Photovoltaic properties investigations indicate that the cell efficiency of QDSSC is close related to the properties of PbS, showing in the order of PbS (hydrothermal, sulfur powder)> PbS (hydrothermal, thiourea)> PbS (chemical corrosion), which is in accordance with their catalytic properties, which can be explained by its different crystallinity of PbS and roughness of the counter electrode.2、Anatase TiO2 crystal of nanometerized particles (-20 nm) and nanorods (-500nm in length) were prepared by a hydrothermal route. The TiO2 crystals were spreaded on FTO to form TiO2 porous films. The film structre was controlled by controlling the kind and ration of different TiO2 crystals. After the deposition of CdS/CdSe quantum dots, the films were used to fabricate QDSSCs. photocurrent-voltage measurements showed that the addition of TiO2 nanorods can effectively increase the photocurrent of the cell. This is further confirmed by IPCE measurement that displays higher IPCE value for the TiO2 nanorod containing cell compared to the bare T1O2 particulate film. The benefit role of TiO2 nanorod is attributed to its increased the light scattering due to its large size of TiO2 nanorod, resulting in the increase of light absorption and the photocurrent of the QDSSC.