Efficient Non-fullerene Organic Solar Cells

Organic solar cells?OSCs?have attained dramatical attention due to their unique advantages of easy solution process,light weight,roll-to-roll production,and flexible device applications.Benefiting from the rapid development of polymer donors,small molecule acceptors,and interfacial materials between molecules and electrodes,more than15%power conversion efficiency?PCE?has been achieved from non-fullerene-based organic solar cells?NF-OSCs?.At present,tremendous efforts have been focused on the promotion of device performance and the commercialization of the NF-OSCs.In this paper,aiming at the device fabrication and performance optimization of NF-OSCs,two methods,the interface modification of NF-OSCs and ternary NF-OSCs are studied.The main research contents are prorated into the following two sections:?1?Monomolecular?3-aminopropyl?triethoxysilane?APTES?was deposited onto Zn O,and act as cathode interfacial layers?CIL?in inverted NF-OSCs.The inverted PBDB-T:IT-M NF-OSCs with Zn O-APTES CIL exhibit a PCE of 11.53%with a high short circuit current density(J_SC)of 18.37 m A cm^-2,an increased open circuit voltage(V_OC)of 0.91 V and fill factor?FF?of 68.77%.More than 13%improvement on the PCE is achieved by inserting APTES,due to efficient charge collection obtained by the enhanced built-in electric field and reduced oxygen defects at Zn O surface.The results indicate that the Zn O-APTES layer is an efficient CIL for inverted NF-OSCs.?2?Ternary NF-OSCs combining two polymer donors?PM6,J71?and one non-fullerene acceptor Y6 were prepared in conventional configuration.The optimized molecular alignment and phase separation in ternary films result a high FF of 76.0%.Furthermore,the complementary absorption spectra of PM6 and J71 can maximize photon harvesting in ternary films that is beneficial to the enhancement of J_SC.The V_OC of ternary NF-OSCs show a monotonously increased trend along with the increase of J71 content,which is attributed to the reduced energy loss based on the similar HOMO energy levels of two donors.As a result,by incorporating 10 wt%J71 in ternary films,the PCE of ternary NF-OSCs achieves 16.5%that is the highest values for ternary NF-OSCs with two donors.The results indicate that ternary NF-OSCs with two donors could achieve high performance by well-optimized photon harvesting and morphology characteristic.