| To deal with the increasingly serious environmental problems and energy crisis,the solar cell technology as a sustainable clean energy technology needs to be developed urgently.Organic solar cells(OSCs),which use organic semiconductor materials as the active layer,have been receiving a lot of attention from domestic and international researchers.OSCs has the characteristics of abundant raw materials,low cost,light weight,non-toxic,flexible preparation,and semitransparency.However,compared with the mature silicon solar cell technology,the power conversion efficiency(PCE)of organic solar cells still has a distance from those mature technologies.Therefore,enhancing the efficiency of the OSCs is still the main focus of research for OSCs.The ternary strategy can effectively improve the PCE of the device.The ternary strategy by adding the third component to the binary system maintains the simplicity of the preparation process of the binary devices and achieves the enhancement of photon capture by the tandem devices.It is particularly important to investigate the effect of the third component on the morphology of the active layer and the mechanism of the internal photophysical process for improving the device performance.In this paper,two different third components were selected to prepare high performance ternary OSCs based on the high performance binary system PM6:BTP-e C9.To investigate the intrinsic mechanism of performance enhancement by means of electrical,optical and thermodynamic characterization of the devices and the active layer.Based on this,the following work has been carried out in this paper:(1)The medium bandgap non-fullerene small molecule acceptor IDIC was added to the PM6:BTP-e C9 host binary system as the third component to prepare PM6:BTP-e C9:IDIC high-performance ternary OSCs.The addition of IDIC enhanced the light absorption of the active layer,optimized the active layer morphology,and obtained a good nanofiber structure and better phase separation,thus promoting exciton dissociation and charge transport and suppressing recombination.The additional F?rster resonance energy transfer from IDIC to BTP-e C9 provides an additional channel for exciton generation and dissociation,which facilitates improved exciton utilization.Its good compatibility with BTP-e C9 facilitates the formation of an "alloy-like" acceptor phase in the mix-blended film,which facilitates the open-circuit voltage enhancement of the device.Finally,the three parameters are all increased when 5wt% of IDIC was added,resulting in a higher level of 18.53% for the PCE ternary device to 17.09% for the main binary device.Ternary devices based on other systems also achieve an increase in device efficiency.This work demonstrates a simple and effective strategy to prepare efficient ternary OSCs by selecting a third component with complementary absorption and good compatibility.(2)The N3,a non-fullerene small molecule acceptor with the same backbone structure but different end groups and side chains with BTP-e C9,was added as the third component to the PM6:BTP-e C9 system to prepare PM6:BTP-e C9:N3 high-performance ternary OSCs.The addition of N3 can enhance the absorption of light for the active layer,which is conducive to the enhancement of the short-circuit current of the device.The N3 can form an energy level cascade model with the main system,which is beneficial to the charge transport and collection.The similar backbone structure makes the two acceptors have good compatibility,optimizes the active layer morphology and phase separation,which facilitating exciton dissociation and suppressing recombination.The ternary devices PCE increased from binary system(17.22%)to 18.54% when 10wt% of N3 was added,which was attributed to the significant increase of short-circuit current and filling factor.This work shows that the selection of a third component with similar structure is an effective strategy for the preparation of funny ternary mailed solar cells. |
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