Structure Modification And Performance Tuning Of Planar Perovskite Solar Cells

Thin-film solar cell is one of the main directions of photovoltaic research, as it has many advantages comparing with other solar cells. Usually, thin-film solar cells are light, cheap, and are easy to fabricate tandem cells. Perovskite solar cell is one kind of the thin-film solar cells. It has been greatly developed during the past few years, which got an efficiency improvement from 3.81% to 20.1%. As a newer perovskite solar cell, planar perovskite solar cell has a more simple structure and is easier to optimize the interface of different layers. It is also easy for mass production. So the planar perovskite solar cells get more and more attention.The research focus on three aspects:carbon electrode, photo anode and perovskite layer, based on the structure of planar perovskite solar cell.Firstly, the fabrication and characterization of carbon electrode were studied. The following structure FTO/dense-TiO2/CH3NH3PbIxCl3-x/Carbon was obtained. Different carbon electrode were fabricated by doctor-blading and screen printing. The micro morphologies were studied, and devices with the two different carbon electrodes were characterized and analyzed. And then, the influence of carbon electrode thickness on device performance was studied.Secondly, different photo-anodes of planar perovskite solar cells were studied. The anodes of TiO2 doped with reduced graphene oxide were prepared and characterized comparing with the traditional TiO2 anode. Using the two kind of photo anodes, planar perovskite solar cells were fabricated with the structure of FTO\Photo anode\CH3NH3PbIxCl3-x\Spiro-OMeTAD\Ag. Two new kinds of ZnO nanorods photo-anodes were fabricated by introducing contact-potential-driven growth and adding PEI. SEM, XRD and PL-spectra indicated that they are well-aligned and crystallized. Devices with the structure AZO/ZnO nanorods/CH3NH3PbIxCl3-x/Carbon were fabricated, and the performance were studied in detail.Lastly, the preparations of perovskite active layer were studied. As the crystallization and surface morphology of PbX2 film have an important influence on the formation of perovskite active layer, so the preparation of PbX2 film were studied first. The influence of different spin-coating speeds and chlorobenzene assisted spin-coating on the PbX2 film formation were studied. Then three methods of perovskite film preparation were discussed, including one-step method, sequential fabrication method and vapor assist method, and the corresponding devices were fabricated. The film prepared by one-step method is ununiformed and discontinuous, and the film prepared by vapor assist method is heterogeneous in composition, which both affect the solar cells performance. The planar perovskite solar cells perform better with perovskite film prepared by sequential fabrication method. The photoelectric conversion efficiency of 6.18% was obtained without the use of additional hole transport layer under an open air condition.