| Perovskite material is a very promising candidate to prepare highly efficient solar cells since its excellent light absorption ability,high carrier migration rate and continuous adjustable energy band,etc.The perovskite solar cell,which was found firstly in 2009,exhibited the certification efficiency has surged from 3.8%to 25.5%during 12 years.The instability of the organic-inorganic hybrid perovskite limited greatly the commercial application of solar cells since the water,oxygen and temperature resulted in the easily decomposition of the organic component.Substituting inorganic element Cs for organic component could resolve the problem of poor stability,providing a potential prospect of solar cell.In recent years,the inorganic perovskite solar cells to explore more deeply and widely,but compared with organic cells,its efficiency is still far behind,and because of all the inorganic perovskite materials itself,can maintain perovskite phase at high temperature,at room temperature is easily into the perovskite phase and limit the whole development and application of inorganic perovskite solar cells.Therefore,to solve these two problems,based on the structure of carbon based mesoporous solar cell,this paper prepared Cs Pb3-xBrx thin film by changing the feed ratio,explored the relationship between the band gap and stability of the thin film,and improved the overall performance of the cell through additive method and anti-solvent method.The main research contents of this thesis.are as follows:(1)Cs Pb3-xBrx films were prepared by one-step spin-coating method.By changing the ratio of Br and I in the precursor,four kinds of thin films Cs Pb I3,Cs Pb I2Br,Cs Pb I1.5Br1.5 and Cs Pb IBr2 were prepared and assembled into a battery.It was found that with the increase of Br-in the perovskite film,the absorption edge and photoluminescence peak gradually shifted blue,the band gap of the film gradually increased,the battery efficiency and short-circuit current density decreased in turn,and the open-circuit voltage increased.The stability of unencapsulated films at low humidity(20-40%RH)air increases with the increase of Br-ratio.(2)Based on Cs Pb I2Br and Cs Pb I1.5Br1.5 materials,the effects of different Cs Ac additions on perovskite films and solar cells were studied.It was found that,for Cs Pb I1.5Br1.5 perovskite films,adding an additional 2.5 mol%Cs Ac to the precursor can improve the crystallinity of the film without changing the crystal structure,improve the coverage rate of the film,passivate the defects at the grain boundary,and thus increase the light absorption intensity of the film.The photoelectric conversion efficiency of the cell was increased to 6.9%,which was 27%higher than that of the control group.The short-circuit current density was 11 m A/cm2,the open-circuit voltage was 1.18 V,and the filling factor was 53.15%.For Cs Pb I2Br,when the addition amount of Cs Ac is 1.25 mol%,the film has the best physical photoelectric performance.When the film is assembled into the battery test device performance,the photoelectric conversion efficiency can reach 11.28%,and the short-circuit current density,open-circuit voltage and fill factor are 14.35 m A/cm2,1.1 V and 71.4%,respectively.Compared with the control group,the cell efficiency is improved by 12%.At the same time,the long-term stability of the two kinds of batteries was improved compared with the control group.(3)The Cs Pb I1.5Br1.5 perovskite films were treated with different volume ratios of trifluoroacetic acid(TFA)and isopropanol(IPA)as antisolvent.It was found that when the mixture of 4%TFA was used as the antisolvent,the perovskite films had larger grain size and higher crystallinity than the control films.At the same time,the light absorption capacity was enhanced and the non-radiative recombination sites in the films were reduced.The final cell has a 7.18%conversion efficiency,and the short-circuit current density,open-circuit voltage and fill factor are 10.52 m A/cm2,1.16 V and 58.83%,respectively,which is more than 30%higher than that of the control group.We also tested the long-term air stability of unpackaged devices,and the results showed that the 4%TFA antisolvent treated cells had higher stability,maintaining 85%efficiency after 24 days in low humidity air. |
PDF Full Text Request