Bulk-heterojunction (BHJ) organic solar cells (OSCs) showcase great advantages in device fabrication via low-cost and convenient solution-processing techniques for diverse applications (e.g., flexible and semitransparent devices) [1,2].Over the past few years, great research efforts have been made for photovoltaic material development and device optimization, pushing rapidly improved power conversion efficiencies (PCEs) for OSCs.The main driving force lies in the innovation of non-fullerene acceptors (NFAs) [3],especially fused-ring electron acceptors (FREAs) featuring acceptor-donor-acceptor(A-D-A) architecture.Classic FREAs are ITIC [4], INPIC-4F [5], COi8DFIC [6] and Y6 [7].Nowadays, 15% efficiency for binary OSCs seems to be a key hurdle for newly designed acceptors.FREAs contributing high performance (PCE > 15%) are still limited, most of which belong to the "Y" family (e.g.Y6, Y11 and BTP-4Cl) [8].In contrast, the OSCs based on classic ITIC series acceptors gradually lag behind in performance.However, the ITIC series FREAs boast their distinct strength in: (i) facile and mature syntheses;(ii) versatile structure modification;(iii) systematic researches on the structure-property relationship.Thus, in order to develop higher performance NFAs, molecular engineering on ITIC is in great demanding.