Growth Mechanism Of Provskite Crystal And The Effect Of Solar Cells Performance

Organic metallic halide perovskite solar cells perovskite solar cells(PerSCs)have drawn a great attention due to their advantages of high efficiency,low-cost,light-weight,and compatible with solution-based roll-to-roll procedures.The power conversion efficiencies(PCE)of the PerSCs have dramatically increased from 3.8%to the current certified record of 22.7%over the past 9 years.The most impressive performance achieved to date has been attributed to the exceptional material properties such as long-balanced carrier diffusion length,high defect tolerance along with low charge recombination,high light absorption over the visible spectrum including a sharp absorption onset and charge carrier diffusion lengths in the micrometer range.Therefore,choosing suitable perovskite film preparation process,researching perovskite crystallization process and expounding the influence perovskite crystallization factors are effective ways to promote the development of perovskite solar cell.Based on the characteristics of perovskite materials,the research on the controllable preparation,mechanism and device performance of the materials is developed in this paper.The main research work is as follows:High quality perovskite thin films have been successfully prepared by vacuum assisted deposition.Alcohol soluble titanium chelate TIPD(titanium(diisopropoxide)bis(2,4-pentanedionate))was used as an electron transporting layer.The devices with the TIPD layer show an enhanced photocurrent due to the remarkably improved charge extraction and suppressed charge recombination.The TIPD layer shows excellent suitability to CH3NH3PbI3 perovskite synthesized by different methods.Selecting a lead source with more volatile byproducts is an effective approach to obtain much smoother perovskite films with smaller and fewer pinholes.Herein,we demonstrate efficient CH3NH3PbI3/PCBM PHJ PerSCs by using lead acetate(Pb(Ac)2)as lead precursor.The perovskite film derived from Pb(Ac)2 shows enhanced surface coverage and improved photoluminescence lifetime in comparison with PbI2 sourced perovskite film.Averaged over 20 individual devices,the power conversion efficiency(PCE)of devices derived from Pb(Ac)2 reaches 14.81%,much higher than PbI2 sourced devices by one-step(8.23%)or two-step(10.58%)spin-coating.It is further studied on the basis of lead acetate as the lead source.The Perovskite Thin Films with large crystalline particles,few defects and smooth and dense are prepared by the slow-growing process.The slow-growing perovskite inhibits the non radiation recombination.Furthermore,the Voc of slow-growing device reaches 1.12 V,which is 0.1 V higher than that of the thermal annealing device(1.02 V).A simple method was used to achieve lead recovery from lead-acid batteries.High purity lead acetate crystals was synthesized,which as lead sources to fabricate the flat structured perovskite solar cells.In the process of synthesis of lead acetate,we preferred the(NH4)2CO3 to have a desulfurization reaction.The PbO2 and PbCO3 from cathode calcined at 550 ? to obtain PbO,and then reacting with dilute acetic acid,the lead acetate crystal was obtained finally.The lead acetate could also obtained from the recation between the lead powder and PbCO3 from anode and acetic acid vapor.The two methods of synthetic acetic acid are relatively simple and with no two pollution occurs.In conclusion,this synthetic path is a relatively green way to recover the lead mud from the waste lead-acid battery.In addition,we also prepared the perovskite solar cell with positive plate structure by using the recycled lead acetate as a lead source.The compact and dense FAPbI3 perovskite films with enhanced crystallinity were successfully obtained by incorporating methylammonium halide(MABr,and MAC1)intermediates through intramolecular exchange processes.An efficient and stable FAPbI3 perovskite solar cell has been obtained.The intermediates play an import role for perovskite formation during thermal annealing.Furthermore,the concentration of metallic lead in the final perovskite film is greatly reduced through intramolecular exchange processes from Br-Hybrid and Cl-Hybrid intermediates,and the metallic lead is almost undetectable in the chloride-hybrid intermediated perovskite.This contributes to the reduction of nonradiation recombination.The PerSCs derived from Cl-Hybrid intermediate exhibit the best photovoltaic performance with a PCE of 19.16%,and the hysteresis decrease significantly.Furthermore,Cl-Hybrid intermediated PerSCs demonstrate the best stability due to the highest crystallinity,We demonstrate high performance Organic Solar cells with dual functional tantalum methoxide(Ta-OMe)cathode interfacial layer,which can reduce the interface energy barrier and form a light trapping structure with reflective metal electrode.XPS results reveal that no by-products yielded in the process of film formation.Ta-OMe shows lower work function than that of acceptors and ohmic contact between the photoactive layer and A1 electrode has been formed,which can minimize the charge injection energy barrier and enhance the build-in electric filed.Furthermore,as proven by SEM and AFM,Ta-OMe tends to aggregate on the surface of the photoactive layer to form large-sized particles.Combined with back-reflection A1 cathode,light-trapping reflection electrode of Ta-OMe/Al is formed and the optical path length of the photons(optical thickness)is increased.