Research On Enhancement Of Absorption Efficiency Of Organic Solar Cells Based On Metal Grating Structure

Organic solar cell?OSCs?was widely concerned due to its advantages of the diversity of material structure,good flexibility and simple preparation process.However,in order to ensure the efficiency of exciton dissociation,carrier transport and carrier collection,the thickness of the active layer of is limited.The attenuation of the active layer thickness will limit the absorption efficiency of OSCs devices.In addition to the research and development of new materials,the device structure also needs to be reasonable design.By introducing trap light structure to adjust the light field distribution in the active layer,the light harvesting is enhanced,so as to improve the absorption performance of the cell.The research content is as follows:?1?In the OSCs of PTB7:PC₇₀BM system,the effect of hybrid Ag grating structure on the absorption efficiency of OSCs was studied.The results show that the broadband absorption enhancement of the active layer covering the visible and near infrared bands can be obtained due to the excitation of surface plasmon resonance and the multiple-resonances of cavity mode.Under the TM polarization mode,OSCs can achieve wide-spectrum absorption from visible to near-infrared bands?350 nm⁸50nm?.The integrated absorption efficiency between 350 nm to 900 nm is57.4%under AM 1.5G solar spectrum and is increased by 13.4%with respect to the equivalent planar device,and the absorption efficiency can reach more than 60%at the wavelengths of 370 nm⁷40 nm?2?In the OSCs of PTB7:PC₇₀BM system,the effect of one-dimensional cascaded grating structure on the absorption efficiency of OSCs was studied.The results show that the broadband absorption enhancement can be realized by exciting multiple surface plasmon resonances modes and these resonance modes at different wavelengths can exist simultaneously in the absorption spectrum.In the range of 355 nm to710 nm,the absorption efficiency of active material can be reached more than 60%.Considering the influence of solar spectrum,the integrated absorption efficiency?350 nm⁹00 nm?of the active layer in TM polarization mode increased from 23.9%,the integrated absorption efficiency of the equivalent plate device,to 54.2%,and increased by126.8%.In addition,when the incidence angle changes within the range of0 to 65 degrees,the absorption band width is basically unchanged.The absorption performance of the device is less sensitive to the slight error of grating parameters and is suitable for the preparation of practical nanometer devices.?3?Based on the one-dimensional cascaded grating structure,the two-dimensional cascaded grating structure is proposed.It can be found that the two-dimensional cascaded structure can make up the defect of the one-dimensional cascaded structure with low absorption efficiency in TE polarization mode,which greatly improves the absorption efficiency of OSCs devices and is independent of polarization.Within the absorption spectrum of 360 nm⁷30 nm,the absorption efficiency of 2D cascaded OSCs is almost all above 60%,realizing the wide spectrum absorption of the device.The integrated absorption efficiency of the active layer between350 nm to 900 nm is 58.9%and is increased by 61.8%with respect to the equivalent planar device?36.4%?.In addition,the high absorption efficiency over 60%can be achieved in 2D cascaded structure at the wide angle from 0 to 60 degrees.