Modification Of Active Layer And Application Of NiOx Film In Perovskite Solar Cell Devices

Perovskite solar cells have attracted much attention due to their high photoelectric conversion efficiency and become a hot spot in the field of solar cell research.Among them,CH2NH=NH2PbI3(FAPbI3)shows excellent optical and electrical properties,and broader potentials for applications with a narrow band gap of 1.48 eV.However,the larger CH2NH = NH2+ cation radius leads to imperfect perovskite crystal structure and heterogeneous perovskite film formation,which is harmful to device performance.In this paper,a novel FAI/IPA surface modification method on FAPbI3 perovskite active layer was proposed to improve the quality of FAPbI3 perovskite thin films and devices performance.The physical and optical properties of the FAPbI3 perovskite thin films were analyzed by XRD,SEM and Uv-Vis measurement.It was found that the re-growth and rearrangement of FAPbI3 perovskite crystals occurs in FAPbI3 perovskitefilms after FAI/IPA solution modification by means of liquid and solid phase diffusion process of FAI,which not only improved the crystallinity of the grain but also changed the surface micro-morphology significantly.The effects of FAI/IPA solution modification on the overall performance of the device were investigated by means of J-V,EQE and PL measurement.The results showed that FAI/IPA modification on FAPbI3 perovskite films not only improved the photoelectric properties of the device,but also enhanced the repeatability and stability of the devices.Finally,the best PCE of 14.00%with a Jsc of 21.75 mA cm-2 and a FF of 0.78 was achieved in low-temperature solution-processed PSCs.PEDOT:PSS is the most commonly used hole transport materias for inverted planar heterojunction PSCs and also has been widely used in organic solar cells and light emitting diodes(LED).However,due to its high acidity and hygroscopicity nature,PEDOT:PSS is not good for long term stability of devices.Therefore is a very meaningful work to find a suitable alternative hole transport materias.NiOx has been demonstrated to be a promising HTM owing to suitable band structure,low cost and good stability.The preparation of NiOx films by laser pulse deposition(PLD)method and traditional sol-gel method exhibit disadvantages of high cost and high temperature,which is not compatible with ITO or flexible substrate and massive production.In this paper,we demonstrate the low temperature solution processed NiOx thin films by means of NiOx ink prepared by our modified sol-gel method,the innovative protocol show improved convenience and reduced cost.When applied on MAPbI3 perovskite solar cell devices,it exhibit a PCE of 17.86%with neglectable hysteresis effect and good photo stability owing to high hole injection ability of NiOx and reduced accumulation of holes in interfaces,which is 42.5%higher than the PEDOT:PSS based devices.