Study On The Performance Of Perovskite Solar Cells Based On Perovskite Layer And Charge Transport Layer

Increasingly severe global energy crisis and environmental pollution have become a concern of the problem,and the development and utilization of clean energy demand is increasingly urgent due to the sustainable development of society and economy in the future.Among many clean energy sources such as natural gas,wind power,hydroelectric power and solar energy,solar energy has attracted much attention because of its wide range of sources,high energy,green and durable features.Solar cell is an effective form of utilizing solar energy,among which perovskite solar cell has become the fastest developing solar cell because of its simple structure,easy preparation and high photoelectric conversion efficiency.However,there are still many factors in the preparation of perovskite solar cells to limit their performance improvement.In this paper,we investigate the performance of perovskite solar cells for its high defect density,low carrier transport efficiency and poor device stability and other problems.By optimizing the perovskite layer and charge transport layer,the interface contact can be improved as well as their own performance,thus reducing the energy loss in the process of carrier transport,increasing the efficiency of carrier transport and collection,and ultimately improving the photoelectric conversion efficiency of perovskite solar cells.The main research contents include:(1)The performance of perovskite solar cells based on Ba Cl2 doping was investigated.Since the radius of Ba2+ was similar to Pb2+ and slightly larger than Pb2+,Ba2+ would partially replace Pb2+ and enter the perovskite crystal lattice,thus cause lattice expansion,increase the grain size of perovskite,improve the quality of perovskite film,adjust the energy level structure,and reduce the non-radiative recombination of interface carriers.At the same time,Cl-could affect the morphology of perovskite thin film,increase the diffusion length of carriers,and improve the transport and collection efficiency of carriers.Through the above optimization process,the photoelectric conversion efficiency of perovskite solar cell with 20 mg Ba Cl2 doping increased from 16.85% to 21.06%.(2)The electron transport layer and device performance were improved by doping Sn O2 with polymetallic ions.Research work 1: x mg KC-Sn O2 composite electron transport layer was formed by doping K+ and Cs+ ions in Sn O2.By controlling the doping amount of Cs+,the conductivity and mobility of the electron transport layer were adjusted to reduce the surface defects of Sn O2 and increased the transport efficiency of carriers.In addition,K+ and Cs+ doping could adjust the energy level matching between the electron transport layer and the perovskite layer,reduced the resistance of carrier interface transport,and increased the fill factor of device.The photoelectric conversion efficiency of perovskite solar cells based on 10 mg KC-Sn O2 electron transport layer was increased from 18.66% to 21.62%,and the fill factor was increased from 72.48% to 81.00%.Research work 2: Sn O2@Na:Cs electron transport layer was formed by doping Na+ and Cs+ ions in Sn O2.Compared with Sn O2 electron transport layer,Sn O2@Na:Cs electron transport layer had higher conductivity and electron mobility,better surface morphology and more matched energy level structure.As the crystal quality of perovskite thin film was improved,the interface defect density was reduced,and efficiency of the carrier transport and collection were improved.By controlling the doping ratio of Na+ ions,the photoelectric conversion efficiency of the device based on Sn O2@Na:Cs(1:3)electron transport layer was increased from 18.39% to 22.06%,and the open-circuit voltage was increased from1.06 V to 1.13 V.(3)The performance of perovskite solar cells optimized based on 2,3,4,5,6-pentafluorophenyl ammonium bromide(5PFP-Br)was studied.Firstly,the surface optimization of the electron transport layer by 5PFP-Br could reduce the defect density of oxygen vacancy on Sn O2 surface and increase its electrical conductivity.The efficiency of electron transport and collection could be improved by optimizing energy level matching and increasing the built-in potential.Secondly,the surface optimization of perovskite thin film by 5PFP-Br was analyzed.Since F-in 5PFP-Br could form covalent bond with Pb2+ in perovskite,the defect density in perovskite was reduced and its stability of structures is enhanced.Meanwhile,the introduction of Brcould optimize the energy level structure of perovskite layer and increase the carrier transport efficiency.Finally,the 5PFP-Br simultaneously optimized the electron transport layer and perovskite layer,and the highest photoelectric conversion efficiency of the device reached 21.15%,and the fill factor reached 80.04%.(4)Optimization of electron transport layer based on sodium copper chlorophyllin.The Scc-Sn O2 electron transport layer was obtained by introducing sodium copper chlorophyllin solution into Sn O2 solution.The introduction of sodium copper chlorophyllin could improve the surface morphology of electron transport layer and increase its electrical conductivity and electron mobility.Good surface morphology of electron transport layer was beneficial to obtain high-quality perovskite film with large grain size.Therefore,interface contact between electron transport layer and perovskite layer was improved,and the interface defect density was reduced,and the efficiency of carrier transport and collection were increased.When the volume ratio of sodium copper chlorophyllin to Sn O2 was 1:15,the photoelectric conversion efficiency of the device reached 19.56%.