Publication date: 8th January 2019
Perovskite solar cells exhibit a rapidly growing efficiency, with a record at 22.7%. These solar cells design can be made of planar layers, or can integrate a mesoporous layer, used as a transport layer, for an efficient collection of the charges. Mesorous layers are, for the majority of the cells, made with titanium dioxide nanoparticles, which forms a compact and non-organized strcuture.
We report here the fabrication of a three dimensional ordered electrode, made in fluorine doped tin oxide, instead of a conventional planar electrode. This structure, known as inverse opal, is widely known for its optical properties, but we use it here for its high surface area. The fabrication of the inverse opal is done in two steps. Firstly, a template made of polystyrene nanoparticles is deposited, by evaporatin induced self-assembly, to form an opal structure. This structure is then infiltrated by a solution of Fluorine Tin Oxide precursors, and is then calcinated, in order to remove the polystyrene particles, and to obtain a crytalline FTO. The quality of the deposited materials is compared with commercial FTO, with XRD and XPS.
The coating of this electrode is done by atomic layer deposition ( ALD), which is a powerfull technique to obtain a conformal coating on complex strcutures, as we investigated. Lastly, the infiltration of the structure with perovskite is done by spin coating, with antisolvent dripping. The perovskite solution dispense is done on the side of the sample, to allow a better infiltration inside the structure.