Encapsulation Of Perovskite Solar Cells And Accelerated Operation Stability Tests At High Light Intensity

In recent years,halide perovskite solar cells(PSCs)have attracted worldwide attention in the photovoltaic field due to their high efficiency and low cost production.However,external stressors such as oxygen,moisture,heat,light,and electric bias will affect the longterm stability of PSCs in practical applications.The main development direction of perovskite solar cells in the future is to further improve the stability and evaluate the reasonable lifetime of the devices.On the one hand,in addition to improving the inherent stability of the devices,encapsulation is another important means to improve the long-term stability of the device.Therefore,in this work,on the basis of the traditional hot-melt encapsulation,the epoxy resin was introduced to outer package devices,so that the devices have a wider and thicker packaging edge to prevent the penetration of oxygen and water molecules.The stability of high temperature and humidity resistance of the device is improved without changing the initial performance of the devices.On the other hand,high light intensity was applied to accelerate the stability test in PSCs.By exploring the relationship between the degradation rate of devices and the multiple of light intensities,this thesis provides a new way to evaluate the stability and study the photo-induced degradation mechanism of devices in a shorter period of time.The main research contents include:(1)In this thesis,the barrier characteristics of different hot melt adhesive(PIB I,PIB II,Bynel,POE)were compared and identified through double 85 aging test,fluorescence spectroscopy,fluorescence spectrographic analysis,X-ray diffraction.Among these hot melt adhesive,the encapsulation effect of Bynel was the best.On the basis of Bynel hot melt adhesive,epoxy resin was introduced to further strengthen the encapsulation performance.The results double 85 test for the device showed that the photoelectric conversion efficiency(PCE)of the device encapsulated by Bynel lost nearly 20% after 500 hours of aging,while the PCE of the optimized package lost less than 5%,which indicated that the optimized encapsulation method could effectively insulate water and oxygen and improve the humidity and heat stability of the device.(2)In this thesis,accelerate light aging test for packaged devices in different ways was performed by adjusting light intensity within 1-8 times equivalent standard sunlight.The test results showed that the degradation rate of the device and the multiple of light intensity accord with the linear law,which suggested that the light stability of the device mainly related to the illumination dose.In addition,the permeability of moisture and oxygen can accelerate the degradation rate,but does not change the dependent characteristics of lightintensity.Through the tests of transient photocurrent,transient photovoltage,photoluminescence and time-resolution photoluminescence,it is proved that the interface destruction and the presence of additional defeats are the main reasons for degradation of the devices when the light intensity is less than 4 times.However,the degradation rate may accelerate under the extremely high light intensity more than 4 times.Because of the accumulation of excessive carriers and the uncontrollable real high temperature of the perovskite film,the degradation rate no longer keeps a linear rule at the high light intensity.Through the above research,the assessment time of the devices can be shortened by at least4 times.