High-efficiency Ternary Organic Solar Cells Based On Y6 Derivatives

In recent years,the remarkable progress of organic solar cell（OSC）research is closely related to the rapid development of organic semiconductor materials and device engineering.It has significant advantages in terms of low cost,light weight,transparency and the additional advantages and photovoltaics contained in the new generation of solar cells.In particular,emerging non-fullerene acceptors（NFAs）and their matching donors have led to leaps in device performance.Currently,single-junction OSCs have a power conversion efficiency of over 19%.However,the absorption spectrum of organic materials is narrow,and OSCs with single Donor and Acceptor have limited photon collection and matching energy.Moreover,the anisotropy of donor and acceptor makes it difficult to control the morphology of the active layer,thus limiting the performance of OSCs devices.Therefore,the three-way strategy has been widely studied.The selection of materials with additional absorption spectra,matching energy levels and good compatibility in the given third group in the binary system is the key to improve the photovoltaic parameters.Because adding the right third component helps broaden the absorption spectrum,enhance the ability of photon capture,improve the energy level matching at the D/A interface,but also adjust the morphology of the active layer.In this work,based on the derivatives of NFAs acceptor Y6,a suitable material was selected as the third component to prepare highly efficient OSCs,and the internal mechanism of improving the performance of OSCs with the introduction of the third component was explored.The main research content of this thesis is as follows:（1）A series of ternary organic solar cells（TOSCs）were prepared by adding BTA3,a non-fullerene acceptor with good compatibility with donor and recipient materials,into PM6:BTP-e C9 binary system as the third component.The addition of BTA3 significantly improves the J_SC and FF of the device,which is due to the widening of the absorption spectrum of the thin film and the increase of photon utilization.In addition,the non-fullerene acceptor BTA3,with 2-（1,1-dichyanomethylene）Rhodanine（RCN）as the electron-deficient terminal unit,has strong electron acceptance ability,which promotes the charge transfer of the device.The best performance was obtained by introducing 5 wt%BTA3TOSCs.The power conversion efficiency was up to 18.65%,short-circuit current density(J_SC)was 27.92 m A cm^-2,open-circuit voltage(V_OC)was 0.865 V,filling factor（FF）was77.19%.This is mainly due to the good compatibility between PM6,BTP-e C9 and BTA3,which optimizes the morphology of active layer,obtains more balanced charge transfer,and inhibits charge recombination.（2）A series of TOSCs were prepared using wide-band gap material D18 as donor,non-fullerene material L8-BO and narrow band gap small molecule N3 with strong near infrared photon capture ability as acceptors.The addition of the third component,N3,to some extent increases the capture of photons,effectively promotes exciton dissociation,optimizes the rate of charge extraction,effectively inhibits monomolecular and bimolecular recombination,and significantly optimizes charge transmission and collection.The two acceptors with similar structures have good compatibility,and the synergistic effect of the two acceptors is conducive to the formation of good phase separation and the optimization of the film morphology.The balance of charge transfer significantly improved the device’s J_SC and FF,and the PCE of TOSCs introduced with 10 wt%N3 reached 18.97%,which was significantly improved compared with binary OSCs.