Study On The Optical Properties Of Perovskite Solar Cells By FDTD-Solutions

Owing to their good carrier transporting performance,high extinction coefficient and direct band-gap,perovskite materials are applied to solar cells.Since the solid-state perovskite solar cell was fabricated in 2012,researches about it are mostly focused on the development of preparing smooth non-porous perovskite membrane,improving the interface contact and some other electrical aspects.However,studies connected with its optical properties are very rare.Therefore,in this paper,we focus on the optical properties of the perovskite solar cell through the time-domain finite-difference simulation and propose feasible measures to reduce its optical loss.Firstly,one method for reducing optical loss of cells was proposed through assembling a layer of PDMS antireflection film with trapping structure on the outer surface of perovskite solar cells.We built the physical model of the perovskite solar cell using FDTD Solutions,and systematically studied the influence on optical properties of the perovskite solar cell from different kinds of light trapping structure(inverted pyramid,inverted circular cone and inverted moth-eye)in PDMS membrane and their dimensional parameters.The results showed that the inverted pyramid structure had its best performance when h=d=4?m,with 2.97% reflectivity of the surface of the cell.And as for the inverted circular cone structure,the lowest reflectivity of the cell's surface was 3.17%,while h=d=3?m.However,the dimensional parameter variation of the inverted moth-eye structure barely had effect on optical properties,with the lowest reflectivity 3.43% when h=4?m,d=3?m.Among these kinds of light trapping structure,the inverted pyramid structure had the best antireflective performance.In addition,the study found that high duty ratio was beneficial to improve the antireflective performance of the structure in order to increase the light absorption of the cell.Secondly,this paper studied the influence of the thickness of the thin films inside on the optical properties of the perovskite solar cell,and optimized the thickness of these films.It is found that the absorptivity of the cell increased with the increase of the thickness of the perovskite layer,and the intrinsic absorptivity and the total absorptivity both reached the maximum number when the thickness was 600 nm.When the thickness of the electron transport layer was 35 nm,the maximum intrinsic absorptivity and total absorptivity of the cell was achieved.After considering the optical properties and the electrical properties,the optimal thickness of the hole transport layer was determined as 250 nm.As for Au electrode layer,the absorptivity of the cell increased continuously with increasing the layer thickness,and the optimal thickness of 60 nm was achieved,at which we could obtained high absorptivity and low cost.In addition,according to the distribution of the electromagnetic fields on the surface of the perovskite layer,we designed an optical coupling structure with double-decker inverted pyramid was designed to further improve photon absorption of the perovskite layer.We designed three different marshalling patterns 4A,4B and 5A in this paper,respectively.Their influence on the optical properties of the cell was studied.The results showed that these three different marshalling patterns all promoted the light absorption of the cell,and 4A and 5A marshalling patterns could increase the total absorptivity of the cell to 97.46%.As for light absorptivity of h 'part in the perovskite layer,4B marshalling pattern could improve the light absorptivity of this part at the extreme.The light absorptivity of h' part was raised up to 110% while the bottom diameter of IP was 4?m.Finally,we prepared multifunctional PDMS films and fabricated perovskite solar cells.And the changes of the photoelectric propertiesof the cells before and after filming were studied.It is found that the short circuit current of cells with PDMS films obviously increased,which showed that the carrier generation rate had been increased,on the other hand,the inverted pyramid structure could reduce reflection and increase the light absorption of the cells.