Research On The Stability And Large Area Preparation Of Perovskite-type Solar Cells

With the continuous consumption of non-renewable energy,the energy crisis is becoming more and more serious.Therefore,as a renewable energy source,utilization of solar energy has been gradually taken seriously.As the third generation of solar cells,perovskite solar cells?PSCs?has become a research hotspot for the active layer has a very high extinction coefficient,the larger carrier diffusion length and bipolar carrier transmission.In order to achieving commercial application,huge efforts should devote to improve the devices stability and realize large area fabrication besides enhancing high performance.Here,we prepared the devices though interface treatment to achieve high performance PSCs and strengthen the stability.Moreover,we fabricated perovskite films with uniform thickness,low roughness and micron crystalline grain via injet printing.And this advantage is good for large area preparation of PSCs.The main research of this paper include the following contents:?1?The polymer polyethyleneimine?PEI?dissolved in two methoxyethanol for interface treatment.The interface treatment layer prepared by spin coating on the hole transport layer?VOX?.Contrast to no treatment,the static contact angle decrease from 30.9°to 15.1°which indicated that the infiltrative was greatly improved after PEI treatment.From the top-SEM,we found the surface coverage of perovskite film increase from 70% to 95%.Cross section SEM illustration the perovskite film thickness increase from 290 nm to 320 nm.X ray diffraction?XRD?showed that the crystallinity of the perovskite was improved after PEI treatment.?2?The structure of PSCs was FTO/VOX/CH₃NH₃PbI_XCl_3-X/PCBM/LiF/Al.After fabricating device,we found that the increased thickness of the perovskite film with PEI treatment enhanced the absorption of light,and increased quantum efficiency.The J-V curves indicted the short-circuit current density was improved,and we achieved the highest PCE of 14.40%.Furthermore,Steady-state PL and electrochemical impedance further demonstrated the improvement of device performance.We added another PEI layer between PCBM layer and electrode to analyze the stability of PSCs.We put the device in the natural environment for 10 days,and the PEI treatment device efficiency declined less than 10% of initial efficiency while the reference device declined more than 90%.The improvement of device stability was attributed to the water absorption of PEI and the performance of storage water.?3?We used superwetted mesoporous TiO₂?m-TiO₂?as the inkjet printing substrate and used different solvents?including DMF,DMSO and mixture?as the ink?20 wt.% PbI₂?.PbI₂ film was fabricated via DMP 2831 ink jet printer.By adjusting the print parameters,setting the substrate temperature and controlling the annealing time,uniform PbI₂ film was prepared by mixture solvent.While the poor PbI₂ film was formed by DMF and DMSO with the surface roughness was about 200 nm.This differences were due to the different melting point and volatility of DMF and DMSO.The perovskite film prepared by mixing the solution had a good flatness with the surface roughness was about 30 nm and the grain size reached the micron level.?4?We fabricated the PSCs with the structure of FTO/c-TiO₂/m-TiO₂/CH₃NH₃PbI₃/spiro-OMeTAD /Au.According to the IPCE and J-V curves,we found the short-circuit current and open-circuit voltage were improved by mixture solution.In attention,steady-state PL and electrochemical impedance further demonstrated the improvement of device performance by mixture solution.We achieved 18.12% PCE.Through this method to prepare an area of 10 cm2 solar cells,and the efficiency up to 10%,which is currently highest efficiency of solar cells reported via inkjet printing technology.