Synthesis Of Bismuth Based Perovskite Films And The Performance Of Solar Cells

Lead-based perovskite thin film solar cells have attracted widespread attention due to their high light absorption efficiency,high charge carrier mobility,high lattice defect tolerance,and adjustable band,so their photoelectric conversion efficiency?PCE?is also growing rapidly.However,lead-based perovskites also have many shortcomings,such as the toxicity of lead and the instability of materials,which seriously hinder the commercialization process.As an earth-abundant and non-toxic element,Bismuth?Bi?is very suitable for new lead-free perovskite materials.In this paper,we have explored a direct metal surface elemental reaction?DMSER?route to fabricate Bi based perovskite thin film,which not only overcome the harm of lead for human body and environment,but also overcome the instability of traditional lead-based perovskite materials.Related research mainly will be investigated as follows:1.The?CH₃NH₃?₃Bi₂I₉ semiconductor thin film was synthesized in-situ on the FTO substrate by using the DMSER route.The method was simple in preparation,low in energy consumption,no organic solvent during the reaction,and different crystal plane oriented films can be obtained by adjusting the reaction time.The XRD results verified that?CH₃NH₃?₃Bi₂I₉ film obained was pure.After being placed in air for 100 days,the film was characterized by XRD,and the results showed that the crystallinity did not change significantly.We studied the photogenerated carrier kinetics of?CH₃NH₃?₃Bi₂I₉ thin film by TPV,and showed that the?CH₃NH₃?₃Bi₂I₉film was a P-type semiconductor material.The?CH₃NH₃?₃Bi₂I₉ thin film material was used as a light absorbing layer to assemble a device with a structure of FTO/TiO₂/?CH₃NH₃?₃Bi₂I₉/Spiro-OMeTAD/Au,and a photoelectric conversion efficiency of 0.03%was obtained.2.The DMSER route was used to synthesize CuBiI₄ thin film in-situ on ITO substrate with different proportion of layered metal bismuth/copper element as precursor.The EDS test results show that there was a gradient concentration change of Bi in the CuBiI₄ film.The results of UV-Vis and PL test showed that the band gap of CuBiI₄ thin film was about 1.8 eV,which was suitable for photovoltaic materials.We combined it with different hole transport materials to obtain the CuBiI₄:HTL bulk heterojunction structure,and studied the photocarrier separation,transmission and recombination in the bulk heterojunction through TPV.The solar cell devices with the structure of ITO/CuBiI₄:PTB7/Au was obtained and achieved a photoelectric conversion efficiency of 1.1%.This method of DMSER at room temperature has laid a good foundation for the development of all-inorganic perovskite solar cells in the future.The innovations of this paper are mainly reflected in the following aspects:?1?The photogenerated carrier behavior of bismuth-based perovskite thin film solar cells was systematically studied for the first time.?2?The synthesis methods of?CH₃NH₃?₃Bi₂I₉ and CuBiI₄ films are elemental direct reaction method.The method is simple and convenient to prepare,which does not need to add any organic solvent during the reaction process and consumes less energy.It is environmentally friendly to preapre perovskite films.?3?Bismuth-based thin film perovskite solar cell has good stability,crystallinity and film quality.This is a potential perovskite film material.