Side chain engineering on D18 polymers yields 18.74power conversion efficiency

摘要

Donor-acceptor(D-A)conjugated copolymers contain-ing fused-ring acceptor units demonstrate outstanding per-formance in organic solar cells(OSCs)[1−13].We have in-vented highly efficient D-A copolymer donors D18 and D18-Cl by using a fused-ring acceptor unit,dithieno[3′,2′:3,4;2″,3″:5,6]benzo[1,2-c][1,2,5]thiadiazole(DTBT)[1,2].OSCs with D18 or D18-Cl gave power conversion efficiencies(PCEs)of 18.56%and 18.69%,respectively[3,4].Side chain engineering is an effective approach to improve the per-formance of conjugated polymers in optoelectronic devi-ces[14−16].The alkyl side chains not only determine polymers’solubility,but also influence their crystallinity and mobility.In this work,we develop two efficient donors D18-B and D18-Cl-B via side chain engineering on D18 polymers(Fig.1(a)).These donors offer PCEs up to 18.74%(certified 18.2%)in tern-ary OSCs.