Large area and flexible CH<sub>3</sub>NH<sub>3</sub>PbI<sub>3</sub> perovskite solar cell fabricated by all ink jet printing

At present, there are many reports on the preparation of large area CH₃NH₃PbI₃ perovskite solar cells based on ink-jet printing. These researches focus mainly on the ink-jet printing and electrode printing of perovskite active layer films. The hole transport layer, electron transport layer and other modified layers in the cell structure are still completed by spin coating or coating. In this work, we successfully realize large area CH₃NH₃PbI₃ perovskite solar cells based on full ink-jet printing, including pen/Ag NWs bottom electrode, agnws top electrode, PEDOT: PSS hole transport layer, etc. It is found that the full inkjet printing can greatly reduce the material cost and simplify the production process, and obtain PC₆₁BM layer, PEDOT: PSS layer, PEI layer and CH₃NH₃PbI₃ perovskite thin film with high density and good uniformity. On this basis, we prepare the CH₃NH₃PbI₃ perovskite solar cells with areas of 60, 80 and 100 cm², respectively. The results show that when the concentration of perovskite ink is 1 mol/L, the printing speed is 30 mm/s and the substrate temperature is 50 ℃, the surface of perovskite film is smooth and the grain size is in a range of 500–600 nm. The surface roughness of the film is only 10 nm, so high-quality perovskite film can be obtained. The power conversion efficiency of the perovskite solar cell with an effective area of 60 cm² is as high as 14.25% (V_OC = 1.03 V, J_SC = 19.21 mA/cm², FF = 72%), which is the highest efficiency of perovskite solar cell prepared by full ink-jet printing method reported so far. In addition, when the device is placed in the air for 12 months without packaging, the photoelectric conversion efficiency is reduced to 80% of the initial value. However, the photoelectric conversion efficiency of FTPU package is reduced only by 5%, demonstrating good device stability.