Performance Of Ternary Organic Solar Cells Based On Dual Non-Fullerene Acceptors

Organic solar cells（OSCs）,a type of solar cell made from organic semiconductor materials,are of great interest to researchers because they are low-cost,lightweight,flexible and easy to prepare.Non-fullerene organic solar cells（NF-OSCs）are currently a hot research topic due to their wider absorption spectrum,higher power conversion efficiency（PCE）and stability.NF-TOSCs are material components in which a second non-fullerene acceptor is used as a third component to expand the spectral absorption range,improve energy level matching,and enhance carrier transport for the purpose of optimising open circuit voltage(V_OC),short circuit current density(J_SC),and fill factor（FF）to enhance PCE.However,further enhancement of its PCE is limited by the narrow light absorption range of the non-fullerene acceptor and the disadvantages of poor energy level matching with the polymer donor and limited carrier transport.In order to solve the problems associated with NF-OSCs,scientists have begun to investigate non-fullerene ternary organic solar cells（NF-TOSCs）.This thesis takes efficient NF-OSCs as a starting point,by selecting suitable non-fullerene materials as the third component,the aim is to improve the efficiency of fundamental physical processes such as photon capture,exciton dissociation and carrier transport,ultimately improving device performance.The role of the third component in the three components was confirmed by analytical methods such as characterisation of materials and testing of the optoelectronic properties of the devices,revealing the intrinsic reasons and working mechanism for the enhancement of NF-TOSCs.The details of the research are as follows:（1）Small molecule non-fullerene acceptor ITIC was used as the third component to prepare highly efficient NF-TOSCs.ITIC can complement the spectral absorption of the binary system materials BTP-e C9 and PM6 to enhance photon capture and boost the photocurrent of NF-TOSCs devices.In addition,the third component ITIC shows good compatibility with the primary acceptor BTP-e C9 and forms an alloy state,the addition of ITIC allows the film morphology to be fine-tuned to form an interpenetrating network fibre structure,which facilitates the formation of a more balanced charge transport and effectively inhibits charge recombination.The results show that the NF-TOSCs based on PM6:BTP-e C9:ITIC have a PCE of 18.25%and an overall improvement in photovoltaic parameters.（2）The green solvent o-xylene（o-XY）was used to replace CB as the main solvent and the non-fullerene acceptor GS-ISO was added as the third component in the PM6:BTP-BO-4F non-fullerene binary system to broaden the spectral absorption and optimise the morphology for efficient NF-TOSCs.GS-ISO is compatible with BTP-BO-4F as a third component,forming an"alloy acceptor"that can synergistically optimise the photon capture,carrier transport and collection capabilities of the three components.In addition,GS-ISO has a strong crystallinity,which enhances crystallisation when added to the binary system and facilitates carrier transport.The results showed that the optimal NF-TOSCs based on PM6:BTP-BO-4F:GS-ISO had a PCE of 18.6%,which was higher than the 16.25%PCE of the binary system based on PM6:BTP-BO-4F.