Preparation And Research Of Ternary Organic Solar Cell Devices Based On Non-fullerene Acceptor

Organic solar cells（OSCs）have enormous potential for commercialization due to their advantages of low cost,light weight,simple process,environmental protection,renewable and flexible preparation.The availability of many highly efficient non-fullerene materials has greatly improved the device performance of OSCs.Interface engineering,the synthesis of novel materials,additives,and the ternary approach of OSCs have all been discovered to be effective ways to improve device performance.Most organic semiconductor materials have constrained absorption range and only a partial coverage of the solar spectrum due to the limitations of organic molecule structure and electronic structure.Although tandem OSCs can alleviate the concerns listed above,their complicated preparation procedure renders them unsuitable for commercialization.Ternary OSCs have a broad solar spectrum coverage while keeping the easy preparation method of single-junction OSCs,and ternary OSCs have become one of the research focus areas.However,there are several issues with OSCs research:（1）The open circuit voltage(V_OC)of OSCs devices is typically low due to material and process restrictions;（2）The current power conversion efficiency（PCE）of OSCs is much lower than that of traditional inorganic silicon solar cells;（3）There has been little research into the operation of ternary OSCs.Therefore,this study uses a ternary strategy to improve the performance of OSCs and investigate its working mechanism.The specific information is split into the two sections below:（1）The small molecule acceptor BTA3 was added into PM6:BTP-BO-4F binary OSCs system to prepare ternary OSCs.First,the complementary absorption spectra of the three materials are conducive to the enhancement of short circuit current(J_SC)of ternary OSCs.Second,BTA3 is compatible with BTP-BO-4F,and its addition can change the morphology of ternary OSCs active layer,accelerate charge transfer within the active layer,and reduce exciton recombination.Furthermore,BTA3 has a slightly higher lowest molecular unoccupied orbital energy level than BTP-BO-4F,which is conducive to increasing the V_OC of ternary OSCs.The energy level and electrostatic potential of molecules were calculated using density functional theory.It was demonstrated that the addition of BTA3 was beneficial to molecule accumulation and exciton separation,as well as promoting charge transfer between molecules.The photoluminescence spectra demonstrate that energy is transferred from BTP-BO-4F to BTA3,which is useful for increasing the device’s exciton utilization efficiency.As a result,the PCE for OSCs increased from 16.46%to 17.69%.（2）The wide band-gap polymer donor J71 was added to PM6:BTP-BO-4F binary OSCs system to prepare ternary OSCs.First,the complementary absorption spectra of the three materials facilitate the enhancement of J_SC in ternary OSCs.Second,it was discovered that J71 has good compatibility with BTP-BO-4F,resulting in terpolymer OSCs with good active layer morphology,which is conducive to improving the fill factor（FF）of ternary OSCs.The energy level and electrostatic potential of molecules are calculated using density functional theory.It is demonstrated that the addition of J71 promotes molecular stacking and exciton separation,as well as charge transfer between molecules.It was discovered by researching charge transport dynamics that the optimized ternary OSCs had more evenly distributed electron and hole mobility.The energy transfer process between the two donors improves the exciton utilization efficiency of OSCs.The results of atomic force microscopy show that the root-mean-square roughness of the ternary active layer is low,indicating that J71 has morphological adjustment function.Therefore,the addition of J71 raises the PCE of ternary OSCs to 17.72%.