Preparations And Performances Of Polyoxometalate Doped Organic Metal Halide Perovskite Photoelectric Devices

Since the beginning of the 21st century,the effective use of solar energy has been regarded as an important direction to solve the current energy crisis.Organic metal halide perovskite has received extensive attention due to its excellent properties among many photoelectric conversion materials.Improving the performance of perovskite photoelectric devices and expanding the application of perovskite materials have become the important research topic.Polyoxometalates?POMs?is a class of electron acceptors can retard the photogenerated electron-hole recombination,and the photoelectric conversion efficiency can be improved by introducing POMs into the perovskite devices as a multifunctional material because of its structural diversity.In this paper,we introduced POMs into the electron transport material of perovskite solar cell to improve its photoelectric performance,and we achieved organic metal halide perovskite into conventional photoelectrode and good performance and stability were obtained.1.In order to solve the problem of low photoelectric conversion efficiency of fully printed hole-free perovskite solar cells,we introduced Keggin type POMs PMo₁₂ into SnO₂electron transport layer?ETL?and replaced the traditional TiO₂ ETL.Because the electron mobility of PMo₁₂-SnO₂ is much higher than that of TiO₂,and the doping of PMo₁₂ can make the position of SnO₂ conduction band move down properly,PMo₁₂-SnO₂ has a stronger ability to capture photogenerated electrons and transfer them quickly to the external circuit.Compared with TiO₂ ETL-based devices,PMo₁₂-SnO₂-based devices increased PCE from10.1%to 12.6%and increased by 28.5%compared with pure SnO₂ ETL-based devices.And because PMo₁₂-SnO₂ has stronger hydrophobicity and lower sintering temperature than TiO₂,it not only improves the stability,but also reduces the fabrication cost of the device.2.In order to give full play to the excellent properties of organic metal halide perovskite materials in the field of photoelectrochemical conversion,a simple perovskite photoanode based on the traditional electrode structure was prepared.Considering that the photoanode needs to be waterproof and transmit photogenerated holes,we use commercial conductive carbon paste and silver conductive paint to coat the photoanode and apply it to photoelectrochemical water splitting.Without the use of co-catalyst,a remarkable photocurrent density of 12.4 mA/cm² at 1.23 V versus reversible hydrogen electrode and the Faradaic effciency was calculated to be more than 80%.Moreover,the photoanode achieves excellent stability,which can be stable in alkaline electrolyte for more than 48 hours,and it keeps steady response of at least 12 hours when it works continuously in strong acid/strong alkali electrolyte.3.In order to solve the problem of insufficient utilization of incident light in perovskite layer,we introduced Weakley type POMs EuW₁₀ containing rare earth elements into the mesoporous TiO₂ of fully printed perovskite solar cells as a material with down-conversion function firstly.The doping of EuW₁₀ can absorb high energy photons in front of perovskite layer and emit low energy photons that match the absorption of perovskite layer,thus stimulating more photogenerated electron-hole pairs.The maximum PCE and J_sc of the devices based on EuW₁₀-TiO₂ mesoporous layer can exceed 14.5%and 23.46 mA/cm²,respectively.Compared with pure TiO₂ mesoporous layer devices,the average efficiency of the cells was increased by 25.7%.4.In order to expand the application of organic metal halide perovskite in the field of photoelectrochemical conversion,we prepared perovskite photocathode based on traditional structure and induced Ostwald ripening of perovskite layer by PW₁₂.The grain size of perovskite is increased,the density of defect states in perovskite layer is greatly reduced,the carrier transport is promoted,and the properties of photocathode are improved obviously.Then,the photocathode was used to reduce carcinogenic pollutant Cr???in industrial wastewater by photoelectrocatalysis for the first time,and a high catalytic activity was obtained.