Flexible Perovskite Solar Cells Based On Woven Fabric Substrate

Perovskite solar cell is a new type of solar cell which has developed rapidly in recent years.It is named after its core material,organic-inorganic hybrid metal halide perovskite CH₃NH₃PbX₃?X=Cl,Br,I?,which possess excellent absorption coefficient and photoelectric performance.To attain further advances,numerous scientists have drawn all attention on optimizing photoelectric conversion efficiency?PCE?of the perovskite solar cell.The morphology control of CH₃NH₃PbX₃ crystal is one of the most important ways.For applicability,the preparation of flexible devices can maximize its manufacture advantages and minimize processing cost.Moreover,it is a great concept of green environmental protection to construct perovskite solar cell on flexible substrate especially on fabrics.In this paper,the novel modification methods of perovskite solar cell have been developed.Secondly,a flexible conductive fabric substrate has been successfully constructed.Finally,perovskite solar cells have been fabricated on this flexible conductive woven fabric substrate with about 1.21%PCE.Main contents of the paper:?1?4-tert-butylpyridine?tBP?,a pore-forming agent,is introduced into the solution of PbI₂.The pore formation of PbI₂ thin films versus tBP concentration has been studied.The porous structure can facilitate the reaction of PbI₂ into CH₃NH₃PbI₃,which dramatically improves the crystal morphology.Field emission scanning electron microscopy?FE-SEM?,X-ray diffraction?XRD?,atomic force microscopy?AFM?and ultraviolet-visible spectrophotometer?UV-vis?are used to characterize PbI₂-tBP and CH₃NH₃PbI₃-tBP films.Experiment results show that as tBP concentration reaches 40?l ml-1,excellent porous structure of PbI₂-tBP film can be obtained.Furthermore,the surface of CH₃NH₃PbI₃-tBP film can get smoother and no excess PbI₂ residue can be detected,which greatly optimize performance of the device.J-V test shows that 7.31%of PCE can be reached.Moreover,due to the residues of tBP in CH₃NH₃PbI₃-tBP films and outside covering effect of the hydrophobic tBP,the moisture stability of the device can be further improved.The PCE could still maintain 70%of the initial PCE after 10 days.?2?Fabrication of conductive fabric substrate.Arising from the layered structure of the perovskite solar cell,which is only about ten to hundred nanometers thick,the surface roughness of the substrate can greatly affect the subsequent work.Fabric/polyvinyl alcohol?PVA?/Nano-silver wire fibers film?AgNWs?conductive fabrics substrates have been fabricated by template-stripping process.As demonstrated by SEM,the surface morphology of conductive fabrics substrates prepared by template-stripping process is quite flat,and without bump phenomenon.The AgNWs embedded in PVA will not affect the surface roughness of the film.The CH₃NH₃PbI₃-tBP film fabricated by spin-coating on the substrate can be well covered without uneven distribution,and the AgNWs film can possess good conductivity and transmittance.?3?The best process parameters for tBP-optimized device performance were applied to fabricate cells on flexible conductive fabric substrates.SEM,XRD and UV-vis results all show that the CH₃NH₃PbI₃-tBP film can be fabricated on the conductive fabric substrate with complete conversion with no excess PbI₂ residue exist.Moreover,the morphology is similar to the film which fabricated on the ITO conductive glass substrate.The final fabric-based perovskite solar cell can advance a PCE of 1.21%.