Study On The Performance Of High Efficiency Organic Solar Cells Based On Active Layer PTB7-Th:PC₇₁BM

Since the 21st century,the expansion and sustainable development of photovoltaic power generation depends on the continuous innovation of photovoltaic materials and technological progress.As one of the rapid development of the third generation of photovoltaic cells,organic solar cells,because of its simple preparation process,light weight,low cost,good flexibility and other advantages by more and more researchers attention.However,there are still many obstacles to achieving the goal of mass production of organic solar cells,and the energy conversion efficiency?PCE?needs to be further studied in comparison with silicon-based batteries and other photovoltaic materials.In this paper,the development history and performance characterization of organic solar cells are introduced in detail,which mainly improves the overall performance of the device by broadening the absorption spectrum of the active solar cell active layer.Based on the PTB7-Th:PC₇₁BM system,a second receptor ITIC,which is complementary to PC₇₁BM absorption,was introduced to prepare the double receptor device.On this basis,1-bromo-4-nitrobenzene and 1.8 diiodo Mixed with different additives on the performance of organic solar cells,to improve the battery surface morphology,increase the short-circuit current density effect.The main research work is as follows:Carrier migration and separation is a key factor limiting the efficiency of organic solar cell conversion.In order to improve the separation efficiency of carriers in the active layer,based on the active layer PTB7-Th:PC₇₁BM of a typical solar cell,a non-fullerene receptor ITIC(3,9-bis?2-methylene?,which is complementary to the receptor material PC₇₁BM,the dual-acceptor organic solar cell was prepared to increase the light absorption of organic solar cells by varying the amount of ITIC doping.The experimental data show that the performance of the device is optimal when the ratio of ITIC is 10%,the short circuit current density(J_sc)is16.41 mA cm^-2,and the energy conversion efficiency?PCE?is increased from 4.31%to 6.17%.The properties of the device were analyzed by UV-Vis absorption spectroscopy and external quantum efficiency.It was found that the ferrite receptor PC₇₁BM was complementary to the non-fullerene receptor ITIC,which could broaden the absorption spectrum and gain more Photons,produce more charge,help to improve the short circuit current,improve device performance.Go further,it was found that the addition of 1-bromo-4-nitrobenzene could affect the performance of organic solar cells.The optimal performance of double-acceptor organic solar cells(PTB7-Th:PC₇₁BM:ITIC?10%?).On this basis,the optical properties of1-bromo-4-nitrobenzene with different mass ratios were increased,and the efficiency was increased from 6.17%to 6.60%,especially the filling factor?FF?,was significantly increased from 47.28%to 53.27%.The effect of 1-bromo-4-nitrobenzene on the performance of organic solar cells was studied by means of basic characterization.It was found that the doping of1-bromo-4-nitrobenzene reduced the generation of fluorescence and accelerated the excitation.The separation of the quantum effectively enhances the device's external quantum efficiency?EQE?.The active layer of the device based on the second chapter is mainly composed of the double-receptor(PTB7-Th:PC₇₁BM:ITIC?10%?)with the best performance.At the same time,1,8 diiodoctane?DIO?.When the addition amount is 2.0 vol%,the device achieves a high photoelectric performance of 8.29%,increasing by 34%,where the short-circuit current density reaches the optimum J_sc=17.21 mA cm^-2.The change of the absorption spectrum of the ternary active layer and the change of the performance parameters of the device were analyzed by UV-visible absorption spectroscopy,external quantum efficiency and atomic force microscopy.It was found that the addition of DIO could optimize the surface morphology of the active layer,Charge transfer has a positive effect,resulting in high energy conversion efficiency.