The origin and evolution of Y6 structure

During last several years,electron acceptors for organic sol-ar cells(OSCs)have experienced three major innovations.The first invention was a fused-ring electron acceptor(FREA),ITIC,reported by Zhan et al.in 2015,which consists of an in-dacenodithienothiophene(IDTT)donor core and two 3-dicy-anomethylene-1-indanone(IC)as the end-groups[1].ITIC cells exhibited comparable performance to PC61BM cells,and in-spired the development of hundreds nonfullerene acceptors(NFAs).The second breakthrough is the 14.08%power con-version efficiency(PCE)delivered by a low-bandgap non-fullerene acceptor COi 8DFIC with strong NIR absorption,invented by Ding et al.[2,3].The third star acceptor is Y6,developed by Zou et al.in 2019[4].Y6 and its derivatives(Y-series NFAs)are very promising[5,6].Ding et al.developed polymer donor D18 and its outstanding derivatives[7−10],and the D18:Y6 cells gave a PCE of 18.22%[7],which was the first time for OSCs to deliver PCEs over 18%.

Star polymer donors

Organic solar cells(OSCs)as a promising photovoltaic tech-nology have attracted great attention due to its unique advant-ages,such as solution processing,low cost,lightweight and ex-cellent mechanical flexibility[1−5].Conventional OSCs always employ fullerene derivatives,e.g.

Stabilization of single atom catalysts

Single atom catalysts (SACs), exhibiting outstanding properties for a wide variety of chemical reactions, have become the most active new frontier in heterogeneous catalysis[1]. Benefitting from the uniform coordination environment, every dispersed single atom in SACs can work as active centers to participate in catalytic cycles, presenting the maximum atom utilization efficiency.