Research On Ternary System And Flexible Organic Solar Cells

The active layer of a binary organic solar cell is usually composed of an electron donor material and an electron acceptor material,and the light absorption by a single acceptor is narrow.Therefore,the introduction of the third component in the binary system not only broadens the absorption of sunlight,but also improves the morphology of the active layer films,balances and increases the mobility of electrons and holes,and reduces carrier recombination.In this paper,two sets of ternary systems are studied,and the binary system is compared with the ternary system to analyze its mechanism of improving efficiency.Then,in the two groups of research objects,the optimal ternary system was used to prepare flexible organic solar cells on flexible substrates,and the photovoltaic performance of flexible organic solar cells under different conditions was discussed.Firstly,PBDB-T:2EH-CPDT-4Cl is used as a binary system.After optimization of the active layer,the photoelectric conversion efficiency reaches 7.39%,and PC₇₁BM was added as the third component to the optimal conditions of the binary system?where the mass ratio of the acceptor did not change?.When the addition ratio was 1:1:0.5,the optimal photoelectric conversion efficiency was 8.04%.Compared with the binary system PBDB-T:2EH-CPDT-4Cl,the photoelectric conversion efficiency is improved,mainly due to the increase of the third component PC₇₁BM in the ternary system,the open circuit voltage is increased,and the absorption spectrum in the near ultraviolet region is broadened,so that the short circuit current density of the photovoltaic device is increased.Secondly,PCE10:F8IC was used as the binary system,and the non-fullerene receptor material IDTBR was added as the third component,the IDTBR could complement the spectrum of PCE10 and F8IC.When the addition ratio is 1:1.4:0.3,the photoelectric conversion efficiency is 10.84%under the inverted device structure,and the photoelectric conversion efficiency reaches 11.62%under the conventional device structure.The photoelectric conversion efficiency of the binary system PCE10:F8IC is 9.34%under the inverted device structure and 9.82%under the vertical device structure,by analyzing the test data,it is found that the short-circuit current density and the fill factor increase are the main reasons for the improvement of the efficiency of the ternary system,and the electron and hole mobility are also improved by the addition of IDTBR.In addition,there is no bimolecular recombination in the optimal ternary system,and the degree of trap recombination is also minimized.Finally,PCE10:F8IC:IDTBR is used as the active layer of the flexible organic solar cell,and the flexible organic solar cell with good performance is prepared by using the inverted device structure on the flexible base.By adjusting the zinc oxide concentration,when the zinc oxide concentration is 55 mg/mL and spin coating at low speed,the highest photoelectric conversion efficiency is obtained,the average open circuit voltage is 0.63 V,and the average short-circuit current density is 16.88 mA/cm².The average factor is 70.37%,the average photoelectric conversion efficiency is 7.46%,and the maximum photoelectric conversion efficiency is 7.96%.The film morphology of the flexible organic solar cell was characterized.It was found that the surface roughness of the active layer reached the lowest value under the optimal conditions,so the photoelectric performance was optimal.