The　development　of　novel　building　blocks　with　sp3-hybridized-carbon-free　conjugated　skeletons　is　important　to　further　advance　and　enrich　nonfullerene　acceptors　(NFAs),　but　this　remains　a　challenge　due　to　the　lack　of　strategies　to　effectively　modulate　the　aggregation　behavior　of　resulting　NFAs.　Herein,　two　novel　nitrogen-bridged　octacyclic　ladder-type　heteroarenes　end-capped　with　thiophene　rings　(BTPS)　or　selenophene　rings　(BTPSe)　are　designed　and　synthesized　as　the　donor　cores　for　constructing　NFAs　(MQX-2　and　MQX-4).　It　is　found　that　replacing　the　sulfur　atoms　(MQX-2)　at　the　outer　positions　of　the　heteroarene　core　with　selenium　atoms　(MQX-4)　can　effectively　modulate　the　molecular　packing　mode　of　the　NFAs.　The　incorporation　of　selenium　atoms　induces　stronger　O···Se　noncovalent　interaction　than　O···S,　thus　promoting　the　formation　of　mixed　H/J-type　aggregates　in　MQX-4.　Benefiting　from　more　electron　hopping　channels,　MQX-4　exhibits　higher　electron　transport　(more　than　1-fold　enhancement)　and　photovoltaic　properties　compared　to　MQX-2,　which　forms　only　H-type　aggregates.　©　2023　SIOC,　CAS,　Shanghai,　&　WILEY-VCH　GmbH.