Two-step Preparation And Performance Optimization Of Full Printable Perovskite Solar Cells

Since the report of all-solid state perovskite solar cells in 2012,the power conversion efficiency?PCE?has increased from 3.8%to 23.7%in recently years,which is comparable to commercial silicon cells.At present,most of the research used expensive hole transport materials,and the noble metal electrode is prepared by the extremely energy-consuming vacuum evaporation method,which increases the preparation cost of the perovskite solar cell and restricts the subsequent large-scale commercial application.In this paper,a carbon-based perovskite solar cell device with a hole-free transport layer is prepared by screen printing technology,which greatly reduces the manufacturing cost.The FAPbI₃-based perovskite devices was prepared by two-step method,and the effect on device performance was further investigated by doping with monovalent cation and halogen anion.The main research contents and results of the thesis are as follows:Firstly,comparing the performance difference between FAPbI₃ and MAPbI₃perovskite,the UV-Vis test shows that the band gap of MAPbI3 and FAPbI3 are1.55 eV and 1.48 eV,respectively.The FAPbI₃ perovskite has better performance of light absorption in the wavelength range of 300-800 nm,therefore,the FAPbI₃perovskite device achieved higher photocurrent,and the PCE was increased from7.48%to 10.81%.XRD was used to monitor the change of FAPbI₃ perovskite film under different environmental conditions.There was no phase transition occurred in FAPbI3 perovskite film under N2 environment,but it was easy to occurred under 60%relative humidity?RH?environment.Due to the hydrophobic action of the carbon counter electrode layer,the phase transition of FAPbI₃ perovskite crystal in the device can slow down.Secondly,the precursor solution was doped with different concentrations of IA group ions?K⁺,Rb⁺,Cs⁺?to investigate its effect on the FAPbI₃-based perovskite.It is found that the doping of K⁺,Rb⁺and Cs⁺ions can improve the crystallization of FAPbI₃ perovskite.While Rb⁺and Cs⁺ions can effectively inhibit the phase transition of FAPbI₃ perovskite,but K⁺ions have no effect on inhibiting phase transition.The J-V test results show that the PCE of the device is significantly improved compared with the control device?10.81%?after doping with 10%Cs ions,and the optimal PCE reaches 11.71%.The optimum PCE of the device after doping 1%K and 1%Rb was10.68%and 11.55%respectively.Under humidity,temperature and light stability tests,it was found that both K⁺and Cs⁺ion doping can improve the stability of the device under three test conditions,and the improvement effect after Cs⁺doping is more obvious.After Rb⁺ion doping,the stability of the device under humidity environment is not improve.Thirdly,the effect on the FAPbI₃-based perovskite was investigated after doping halogen anion Br^-in the precursor solution.It was found by XRD that no characteristic peak of yellow phase?-FAPbI₃ after Br-doping,indicating that the introduction of Br^-ion can inhibit phase transition of.In the J-V test,the device had an optimum PCE of 11.53%when doped with 10%Br concentration.However,the phase transition of FAPbI₃ perovskite still occurred in long-term storage.In order to further improve the PCE and stability of the device,10%Br-Cs was doped in the precursor solution,and the champion device has a PCE of 14.14%was prepared by continuously optimizing preparation process.In the long-term stability test,it was found that the 10%Br-Cs devices unencapsulated still had an initial PCE of 87.0%for 120 days under amient environmment.After encapsulation,the 10%Br-Cs devices were tested by thermal cycling and found that there was still 102%of initial PCE after 100 cycles.It is demonstrated that the 10%Br-Cs device has excellent thermal stability.