Structure Design And Properties Of Hybrid Solar Cells Based On Lead Iodide Perovskite

Recently, the material based an organic-inorganic perovskite-structure as a newcomer to the photovoltaic field has been rapidly developed, due to its high charge-carrier mobilities and high charge carrier lifetimes, controllable bandgap, easily deposited by low-temperature solution methods. But these solar cells have some disadvantages such as the instability in the air and high cost of the hole transport materials (HTM) and the black electrode materials. This dissertation prepararend high performance lead iodide perovskite by two-step deposition.Then explored a low cost planar-junction perovskite solar cell, with the P3HT as the HTM and carbon nanotube (CNT) films as the back eletrode. Further a fiber-shaped was fabricated wirh an ideal stability and considerable efficiency.The CH3NH3Pbl3 perovskite layer was fabricated with lead iodide (PbI2) dissolved in N,N-dimethylformamide (DMF) and methylammonium iodide (CH3NH3I) dissolved in 2-propanol.When the molar ration of CH3NH3I to Pbl2 was 1:1,the CH3NH3PbI3 was a pure phase with a tetragonal perovskite structure. The band gap was about 1.56 eV and the property of the photoelectricity reponse was great, confirming feasibility of the absorber layer for the solar cell.Then the author assembled a planar-junction solar cell with the structure ITO/TiO2/CH3NH3Pbl3/P3HT/CNTs. The optimized perovskite solar cells obtained a power conversion efficiency(η) of 0.13% under standard illumination (AM 1.5,100 mW cm 2), in which the parameters of the open-circuit voltage (Voc), short-circuit current (Jsc) and fill factor (FF) were 0.696 V,0.718 mA cm 2 and 0.252 respectively.The electron transport layer was about 160 nm and the perovskite absorbing layer was about 750 nm.On the basis of the planar-junction, combining with the peroviskite and CNTs film, the author assembled a fiber-shaped solar cell with the structure Ti/TiO2/CH3NH3PbI3/P3HT/CNTs. TiO2 nanotubes arrays were formed by anodizing the Ti wire, and its structure was influenced by the different conditions. The best TiO2 nanotubes for the solar cell had a length of 680 nm and a diameter of 30 nm.The optimized solar cells had a conversion efficiency (η) of 1.92% under standard illumination (AM 1.5,100 mW cm 2), with the Voc of 0.717 V, the Jsc of 5.083 mA cm 2 and the FF of 0.527. The stability testing showed a little decrease in efficiency of nearly 23% after about 300 hours. The performances were great with the series-coupled cell, the parallel-coupled cell and the change of the bending angle. Compared with the planar-junction solar cells, the fiber-shaped solar cells could be woven into textiles via some weaving technologies and used for the portable power source.