Simple‐Structured Acceptor with Highly Interconnected Electron‐Transport Pathway Enables High‐Efficiency Organic Solar Cells

Achieving desirable charge‐transport highway is of vital importance for high‐performance organic solar cells (OSCs). Here, it is shown how molecular packing arrangements can be regulated via tuning the alkyl‐chain topology, thus resulting in a 3D network stacking and highly interconnected pathway for electron transport in a simple‐structured nonfused‐ring electron acceptor (NFREA) with branched alkyl side‐chains. As a result, a record‐breaking power conversion efficiency of 17.38% (certificated 16.59%) is achieved for NFREA‐based devices, thus providing an opportunity for constructing low‐cost and high‐efficiency OSCs.