Electrode Structure And Properties Of Quantum Dots Sensitized TiO₂Nanocrystalline Solar Cells

Quantum dots sensitized solar cells(QDSCs), as a new type of solar cell, are regarded as potential low-cost and high efficient alternative to conventional Si-based solar cell. However, the performance of QDSC is significantly influenced by semiconductor oxide, quantum dots, counter electrode and electrolyte. For the purpose to improve the performance of QDSC, we have prepared the photoanodes based on CdS quantum dots sensitized TiO2porous film and TiO2nanotube arrays and CuInS2quantum dots TiO2nanotube arrays, and the carbon counter electrode, and studied the performance of the quantum dot sensitized solar cell based on these electrodes. The main results and conclusions can be summarized as follows:1. TiO2nanocrystalline porous film is prepared by screen printing method. The effects of the screen printing cycles on morphology and structure of TiO2porous film were studied. CdS QDs sensitized TiO2porous film was prepared by successive ionic layer absorption and reaction (SILAR) method and its photovoltaic performance was studied. The results show that for I-/I3-electrolyte/Pt counter electrode system, both the thickness of TiO2porous film and CdS QDs deposition amount can influence the QDSC’s photoelectric conversion performance. With the increasing film thickness and CdS QDs deposit amount, the photovoltaic performance of QDSC first increases to maximum and then decreases.2. Carbon counter electrode on FTO conducting glass is prepared using activated carbon as raw materials. The effect of counter electrode on the photovoltaic performance of polysulfide electrolyte based QDSC. The results reveal that, carbon counter electrode prepared by doctor blade method can obviously improve the photovoltaic performance of QDSC. From the EIS analysis, carbon counter electrode reduces the resistance on the counter electrode/electrolyte interface, and is benefical to charge transfer.3. TiO2nanotube arrays are prepared by constant voltage anode oxidation, and sensitized by CdS QDs. The photovoltaic performance of CdS QDs sensitized TiO2nanotube arrys in polysulfide electrolyte is studied. The results show that with the increasing CdS QDs depositon amount, the photoelectric conversion efficiency of CdS QDs sensitized TiO2nanotube arrays solar cell increases to a maximum and then decreases. In the same other conditions on polysulfide electrolyte/Pt counter electrode, Jsc of QDSC based TiO2nanotube arrays is higher than that of QDSC based on TiO2nanoparticle film. This result demonstrats that the higher area surface ratio of TiO2nanotube arrays can be beneficial to deposit CdS QDs.4. Ternary sulfide CuInS2QDs are synthesized by solthermal method. The CuInS2QDs are deposited on TiO2nanotube arrays functioned by bifunctional linker to prepare CuInS2QDs sensitized TiO2nanotube arrays. The photovoltaic performance of CuInS2QDs sensitized TiO2nanotube arrays solar cell is studied. The results show that the efficiency of pre-synthesized CuInS2QDs sensitized solar cell is relatively low.Using CuInS2/CdS co-sensitized TiO2nanotube arrays,can improve the efficiency of the solar cell.