Quantum Dot Sensitized Solar Cell: Preparation And Improvement Of The Power Conversion Efficiency

The development of high-performance solar cell is of great significance in solving the energy crisis and development of low-carbon economy. Quantum dot-sensitized solar cell (QDSSC), a third generation solar cell with higher theoretic power conversion efficiency (PCE) and lower cost, have attracted the attention of many scientists in the solar cell area. So far, however, the PCE of QDSSC is still much lower than that of the traditional solar cells.In this thesis, considering that the synthetic processing, existance of defects in materials, configuration of energy levels can greatly influence the PCE of QDSSC, wedesigned a CdS/ZnO heteronanostructure as anode material, adopted chemical bath deposition and hydrothermal technique as synthetic methods, and controllaby synthesized the CdS quantum dots (QDs) and ZnO nanowires (NWs) arrays.We investigated the effect of annealing treatment on the PEC of the CdS QDSSC. The thickness of CdS layer and the annealing temperature were found to be very crucial for the performance of CdS/ZnO solar cells. The PCE was improved significantly after annealing treatment, which could be attributed to the enhancement of the absorption ability, decreasing the defects of anode materials and the formation of a diffusion layer between the CdS shell and ZnO core.Dual-sized CdS quantum dots were employed as light harvesters to achieve high PCE. Chemical bath deposition and annealing treatment were adopted to produce CdS quantum dots with different sizes. The strategy of co-sensitization by dual-sized CdS quantum dots could significantly improve the performance of solar cells by forming a type-I band structure. This work indicates that the proper configuration of quantum dots is crucial on the photovoltaic conversion of solar cells.We developed a self-sensitized solar cell with CdS porous structure as the anode material. The CdS porous structure, assembed by high-density CdS nanocrystals, was synthesized by hydrothermal method and could effectively realize the photovoltaic conversion. The CdSe/CdS co-sensitized structure, another self-sensitized system with CdSe nanoparticles on the CdS porous structure, was obtained via electric deposition, which further, improved the performance of the solar cell.