Theoretical Study Of Using Arrayed Silver Nanostructures To Improve The Light Absorption In Organic Solar Cells

Over the past two decades,metal nanostructures have been widely used in organic optoelectronic devices as one of the most popular structures of light-trapping structures.In this paper,we use the material PTB7: PCBM as active material,and the simulation method are the finite element method and the finite difference time domain method.Different arrayed silver nanostructures having an effect on the light absorption performance are introduced in organic solar cells.Specifically include:1.We optimized the thickness of active layer of the inverted flat organic solar cells.and obtained the optimal thickness is 104 nm,at this time,the active total absorption is 70.2%.2.We studied the property of strengthening light absorption by using one–dimensional(1-D)silver nano-strip array.The optimal parameter values are period(p = 300 nm),duty cycle(r = 0.15),high(h = 30 nm),and the distance to the bottom of active layer(d = 20 nm).With the optimal parameters,the light absorption of the active layer enhanced 7.63% relative to the reference.The rich photon mode and surface plasmon are excited in active layer.Also,the four parameters(p?r?h?d)have a vital guidance on the light absorption performance of active layer.when h(r)is high,the active layer of light absorption reaches the maximum value corresponding to the smaller value of d(r).3.We studied the property of strengthening light absorption by using two-dimensional(2-D)silver nano-slice array.Obtained the optimal parameter values: p = 1300 nm,r = 0.5,h = 45 nm,and d = 5 nm.With the optimal parameters,the light absorption of the active layer enhanced 7.57% relative to the reference.Also,the rich photon mode and surface plasmon are excited improving the field intensity distribution in active layer.With the increase of duty ratio,the sensitivity of the solar cell device for small period increases quickly,while for large period increase slowly.4.Finally,We analyzed the effect of morphology of 2-D silver nanostructures on strengthening light absorption properties in organic thin film solar cells,including 2-D silver nano-slice-array transformed to 2-D silver nano-cross array and 2-D silver nano-annular-array.It is all concluded that the silver nano-slice-array structure is superior to the crossarray and annular-array in enhancing the light absorption in organic thin film solar cells.We designed organic thin film solar cells based on 2-D silver nanoslice array,which has a large period and compares with those complex grating structure,they are easier to produce.