Preparation And Properties Of Flexible Perovskite Solar Cells

Flexible perovskite solar cells(F-PSCs)can be used in portable energy,aircraft and electronic textiles due to their light weight and flexible.The power conversion efficiency(PCE)of perovskite rigid devices has increased from 3.8% to 24.2%,but the PCE of F-PSCs is always poor than devices made on rigid substrates using the same process.This is mainly due to some properties of the commonly used flexible substrate(PET/ITO).For example,the thermal expansion coefficient of PET and ITO does not match,resulting in its easy bending in the heating process,resulting in cracks in the perovskite film.ITO is easy to break due to its brittleness,which reduces its mechanical stability.F-PSCs also have the potential for large-area roll-to-roll production,but the traditional process of vacuum coating equipment to deposit the precious metal as the top electrode does not use large-area roll-to-roll production.In addition,fibrous perovskite solar cells can be used in the field of electronic textiles,but the preparation process has certain technical difficulties.In view of the above problems in the F-PSCs,this paper studies from the following two aspects:(1)For the mismatch between the thermal expansion coefficients of PET and ITO,the substrate is easily bent during the annealing process,causing cracks in the perovskite film to reduce the quality of the perovskite film.In this paper,a gradient heat treatment(GHT)method is used to prepare a perovskite film.Results show that the perovskite films surface crack is obvious disappear with temperature gradient decreases,and grain size gradually increased from 0.6 ?m to 1.2 ?m.Meanwhile,edges and corners also be more and more uniform,in developing in the direction of the single crystal is changed,when the temperature gradient is small to a certain degree,the shape of the perovskite grain almost close to the single crystal shape,its crystallinity increase with the decrease of the temperature gradient in gradually.Secondly,with the decreasing of the cooling gradient,the optical absorption intensity of perovskite film is gradually enhanced,and the peak intensity of photoluminescence is also gradually enhanced,which proves that the optical characteristics of perovskite film are also enhanced with the decreasing of the cooling gradient.Compared with the conventional method,the PCE of F-PSCs fabricated by a GHT process with relatively small gradient has been significantly improved by 31%,and the maximum PCE has increased to 17.37%.(2)Due to ITO is brittle and easy to break and the top electrode needs to be deposited by high vacuum equipment.In this paper,silver nanowires with high conductivity and a certain light transmittance are used to replace the traditional electrodes.And the preparation of fibrous perovskite solar cells on non-conductive fibrous substrate was realized.Perovskite solar cells with an efficiency of 2.83% were prepared by using silver nanowires as the top electrode on a planar substrate.Then a fibrous perovskite solar cell was prepared on the capillary tube using silver nanowires as the top electrode and the bottom electrode.The prepared perovskite grain grows as a penetrating grain longitudinally,which can promote carrier transport.