Preparation And Performance Study Of Hole-Transport-Layer-free Carbon-based Perovskite Solar Cells

The high performance and simple manufacturing process of perovskite solar cells（PSCs）have attracted more and more attention in the scientific community.Over the past few years,emerging technologies have made it possible to manufacture large-scale PSCs.However,the application of hole transport materials（HTM）and precious metal electrodes（Au or Ag）in traditional PSCs structure is expensive and unstable in ambient air,which accelerates the attenuation of the device and increases the production cost,which hinders the production scale and practical application of PSCs.Therefore,in order to solve the above problems,this paper reduces its cost on the basis of higher photoelectric conversion efficiency,replaces precious metals with carbon as the counter electrode of the battery,and introduces carbon electrodes by coating without using expensive hole transport layers improve device performance.The research content of the paper is as follows:（1）From the perspective of reducing the production cost of perovskite solar cells,using conductive carbon paste as the carbon electrode,a two-step spin coating method was used to prepare the perovskite film,and it was found that the prepared CH₃NH₃PbI₃ had a small grain size,incomplete crystallization,and there were holes and defects exist.The prepared perovskite thin film was applied to the manufacture of carbon-based perovskite solar cells without hole transport layer.A mesoscopic perovskite solar cell with FTO/c-TiO₂/m-TiO₂/CH₃NH₃PbI₃/C structure was preliminary explore.The energy conversion efficiency（PCE）of the perovskite solar cell prepared using the carbon electrode is 4.26%,and the photoelectric conversion efficiency of the unpackaged device after being placed for 360 h is about 50%of the initial efficiency.（2）Through solvent engineering,the film-forming quality of perovskite thin films is improved.A mixed solution of PbI₂ in N,N-dimethylformamide（DMF）and dimethyl sulfoxide（DMSO）was used as a precursor solution.Two-step spin coating method was used to prepare CH₃NH₃PbI₃ film and PSCs.The effects of different solvent ratios on the film formation quality of perovskite thin films and the photoelectric performance of battery devices were explored.The use of DMF and DMSO mixed solvents can effectively improve the conversion rate of the precursor and reduce the PbI₂ residue in the perovskite film.By adjusting the ratio of DMF and DMSO solvent in the precursor solution,the crystallization process of the perovskite can be effectively adjusted,the surface morphology of the film can be improved,and the crystallinity of the perovskite crystal can be improved.When the solvent ratio is DMF:DMSO=9:1,at this time,the quality and crystallinity of the prepared perovskite thin film are better,and the PCE of the perovskite solar cell prepared based on the thin film reaches 7.82%.（3）We provide a simple,effective,and low-cost strategy to improve the quality of perovskite films,introducing 4-tert-butylpyridine（TBP）additive into the perovskite precursor solution,and exploring the introduction of TBP to perovskite the effect of thin film quality and the photoelectric performance of battery devices.Through the induction of TBP additive,a relatively dense and uniform perovskite film is obtained,which improves the grain size and light absorption performance of CH₃NH₃PbI₃,reduces the defect state density of the perovskite film,thereby improving the photovoltaic performance of PSCs and the best device PCE reached 11.22%.At the same time,PSCs devices showed a lower degradation rate under ambient air condition with a humidity of 40%,and PCE maintained more than 80%of its initial value after 360 h,thereby greatly enhancing its stability in water vapor.