Oxidation Doping Of Hole Transport Layers And Interface Control In Planar Heterojunction Perovskite Solar Cells

With the continuous increase of total energy demand,the pace of optimization and adjustment of energy supply structure has been accelerated.Solar photovoltaic technology is expected to become the most effective solution to relieve the pressure of current environment and energy supply.As a typical representative of the third generation of new solar cells,perovskite solar cells(PSCs)have become a new research hotspot due to its advantages of solution preparation,low cost,high absorption coefficient,adjustable band gap and double-carrier transmission characteristics.After ten years of development,the photoelectric conversion efficiency(PCE)increased from the initial 3.8% to 25.2%,and the integrated photoelectric performance of PSCs was improved by leaps and bounds.However,there are still many problems to be solved to realize commercial large-scale practical application.In view of the current status and problems of PSCs,this paper focuses on improving HTL conductivity,hole extraction efficiency,perovskite film quality,PCE and stability of device.The main experimental content and conclusions are as follows:(1)In PSCs,the conductivity and carrier extraction of HTL is of great significance to improve the PCE of device.In order to optimize the photoelectricity of HTL,we first introduced iodine to the spiro-OMeTAD solution as an oxidizing p-type dopant,and effectively increase the content of oxidized state spiro-OMeTAD cationic radicals in HTL,thus improving the overall photoelectric performance of PSCs.Through UV-vis,PL,TRPL,Tafel,ESR characterization methods to explore and prove the performance improvement mechanism,and the simulated solar system was used to test the photoelectric performance of cells.The results show that doped of iodine effectively improves the content of cationic radicals,carrier extraction efficiency and device photoelectric performance.PCE of the optimal experimental group was 19.69%.(2)Potassium persulfate(KPS)was introduced into HTL as a p-type dopant,and its strong redox potential were used to effectively oxidize spiro-OMeTAD,increase content of cationic radicals in HTL,improve the hole conductivity and extraction capability of HTL,optimize energy level matching with perovskite,and thus enhance the PCE of PSCs.FESEM and AFM characterization techniques are used to study the effect of doped KPS on HTL surface roughness and device structure.UV-vis,Tafel,PL,TRPL,ESR and other characterization techniques are used to analyze the mechanism of PSCs efficiency improvement.I-V and IPCE characterization are used to test the photovoltaic performance of the cells.The results show that doped of KPS effectively improve the conductivity,hole extraction efficiency of HTL and PCE of device.PCE of the optimal experimental group was 20.00%.(3)For the first time,12-Crown-4,which has both interface modification function and excellent Li ion capture ability,was introduced between perovskite/HTL interface,through interface modification treatment to improve the quality of perovskite film,reduce the density of defect states and non-radiation recombination,improve carrier transport performance,and also use the excellent Li ion capture ability of 12-Crown-4 to suppress the migration and diffusion process to perovskite,thereby improving the PCE of PSCs devices and stability.Through FESEM、AFM testing technology study the influence of modification on surface morphology,roughness of perovskite film and deviece structure.Using UV-vis,UPS,PL,TRPL,EIS measuring technique analysis carrier transport,energy level,transfer resistance,study the mechanism of photoelectric performance improvement,and the secondary ion time-of-flight mass spectrometry(TOF-SIMS)test was to study the longitudinal depth Li ion distribution and stability of device.I-V test system was used to characterize the photoelectric performance of PSCs.The results show that introduction of 12-Crown-4 interface modification layer significantly improves the PCE and stability of PSCs deviece.The optimal experimental group achieved 20.44% PCE.